Phase I, "Establishing the physico-chemical characteristics for origin controlled amber (succinite and romanite)", has been projected as a content phase, directly conditioning the investigation, in the following phases, of archaeological amber. The theme complexity which makes the object of debate in literature, the need to refer at different analytical techniques, made us planning this phase for a period of six months. Due to reasons which do not necessary represent our will, the first phase (phase I) lasted only three months, until the end of the year. Therefore, the Romanit consortium tried to fulfill ambitious objectives in a very short period of time.
- Several activities, aiming to prepare the main ones, took place during this phase:
- identification of origin controlled amber pieces, available and accessible for analyses within the consortium (Activity I.2, see tables 1 and 15)
- establishing an inventory of the archaeological pieces within MNIR which may be classified for analyses in the Romanit project according to their characteristics; 180 adornment assemblies were selected for investigation (Activity I.5); contacts with several museum in Romania were also established in order to recommend archaeological pieces to be included in the project: a protocol was already signed with the Eco-Museal Institute Tulcea;
- elaboration of a database where all the information regarding the adornment pieces together with data on controlled origin amber sources will be uploaded. Queries in the database will result - in a dynamic way - in the list of materials used in Roman and post-Roman adornments manufacture (Activity I.6, see Fig. 1 and 2).
- Other activities from the "dissemination" spectrum have also been accomplished:
- the press conference held on the 19th of October, 2007 at the National Museum of Geology, on the occasion of an exhibition on Tara Buzaului (Buzaului County) amber. The conference aimed to point out the beginning of one of the most ambitious projects dedicated to amber investigation (Activity I.1)
- establishing the nucleus of the Students' Archaeometry Group, the first public meeting being held on the 22nd of November, 2007 (Activity I.4)
- creating the design project for the www.romanit.ro site (Activity I.7), active since the 5th of December, 2007.
The most laborious activity, and the one with the biggest stake, was Activity I.3, Physico-chemical measurements on origin controlled amber samples. This is the activity we'll refer to in the next part of the abstract.
Romanit Laboratory was established in MNIR and equipped with all the necessary instruments for the primary study of the amber sources and adornment pieces: image capture, weighting, measuring, database registering, and sampling (see Fig. 3). One hundred samples were collected here from each source 1 (Baltic amber) and source 3 (Buzau amber), and sent to the three analytical laboratories from the consortium. Subsequently, another 50 samples have been taken from other sources, the 250 samples becoming thus the experimental base of the project. The main aim in experimental phase I was to establish the typical features of Baltic amber, by comparing it with the romanite, in concrete technological situations. The great resemblance between the two materials - quasi-identical from the chemical point of view - as well as the peculiar complexity of the mineraloid, represented a great challenge.
According to literature, the most suitable analyze is FT-IR (Fourier Transformed Infrared Spectroscopy). Two different teams were brought together in the project for FTIR analyzes, in order to assure the mutual reference of the results, in the conditions of a competing investigation. The first research team is the one of Partner 1, who collected the spectra in transmission mode, by embedding the powdered amber sample in KBr pellets. The second research team - Partner 4, the second research team, of Partner 4, INSB, used both transmittance and reflectance variants, expressing, however, at the end of the investigation the preference for the reflectance variant. The latter analyze variant also presents pure analytical advantages (the material is not destructured through trituration, but at the same time significant museographical advantages, due to the fact that the method does not imply sampling; nevertheless, the dimensions of an object for analyze cannot exceed 15 mm
The comparative results of the two FT-IR analyze research teams are remarkably similar, transforming thus into a successful experiment of the competing investigation. Moreover, the results proved that the method can be profitably used, in both technological variants, for the separation of Baltic amber from the Buzau amber. Apart from underlining the well-known C. W. Beck's "Baltic shoulder", the two research teams managed to highlight other areas of interest in the amber spectra, where succinite and romanite seem to have distinct behavior, firstly due to their different age: 3400-3600 cm-1, 1350-1820 cm-1 and 800 cm-1, elements which represent original contributions at the amber chemistry at this stage of documentation.
The results of the two analytical methods - TD-GC-MS gas chromatography and simultaneous thermal analysis - performed at Partner 5, allowed as well the reproduction of certain techniques consecrated by the archaeometric literature.
Partner 2 offered the consortium a generous documentation concerning amber genesis, its geographical recurrences, paleontology and perishability. This contribution was supplemented by a brief study on the mineralogical and physico-chemical properties, enriched at Partner 3 - the University. A microscopic study has been undertaken here as well, confirming - on the reference material of the project - the crystallization tendency of romanite, unlike the succinite, raising thus the possibility of using the difractometry method for the differentiation of the two amber types. The microscopic study led to the identification of fossil wood and several fossils from Insecta and Arachnida classes.
The results of phase I, although will demand consolidation, on a larger lot of samples, are very satisfying and represent a thorough base for the study of amber with an archaeological origin.
Eugen S. Teodor
The specific objectives of the execution phase are resumed by the title of phase I - Establishing the physico-chemical characteristics for controlled origin amber samples (succinite and romanite). The title defines the strategic objective of the phase, namely the "print" identification specific to both amber type circulated on the territory of Romania - the name used in the international literature for Romanian amber, especially for the one coming from the basin of Buzau (known as well as "Colti amber"). All the technical means that have been available for the Consortium were used in order to accomplish this objective (see Activity 1.3 from the Realization Plan).
In the Realization Plan we have foreseen other activities as well. Thus, an activity group will constitute in preliminatory activities, for the current phase, or for phase II of the project (the later comprising both sub-phases of 2008). Consequently, activity I.2 consists in identification of the origin controlled amber, available for analyze; activity I.5 foresaw the inventorying of the archaeological pieces which represent an interest for the objectives of the project, available in the inventory of the Romanian National History Museum, but as well those available in the patrimony of other muzeal institutions; activity I.6 forecast the inventorying of the natural materials identified in the componence of the archaeological pieces. All these objectives have been systematized in a data-base, hereunder described (see Scientific and technical description).
In the realization plan we have comprised dissemination activities, beginning with a press conference (I.1), establishing the Archaeometry Students' Group (I.4), and finalizing with the design of the project's web-site (I.7), namely the determination of the structure, the graphic, acquisition of the domain and performing the functioning tests.
Eugen S. Teodor
Decision and communication mechanisms
We shall shortly describe the decision organization and management modality
In order to launch the project, we have established a forum (http://tech.groups.yahoo.com/group/romanit/), even since May 2007, forum which we called "Romanit". This forum was very important especially during the consortium's organizational period, but also after the official establishment of the activity. The forum is not only a permanent communication method, but as well a depositary of the information resources, comprising an incipient data-base (bibliography, institutions, members, links, and also several pdf articles). In this way, we managed to reduce the number of meetings of all the members at the same time. We used the public activities of the Consortium (Press conference at the National Geologic Museum, from 19th of October 2007, and the establishing of the Archaeometry Students' Group, from 22nd of November 2007) to organize short operative discussions, regarding the activity within the Consortium, but also to establish a dedicated organizational meeting.
The activity of the Consortium, during the first execution phase, has been oriented on two major segments, namely the analytical activities and the geologic substantiation. If for the later Partners 2 and 3 (IGR and UBFGG) might have performed relative independent activities, the analytical activities had to be coordinated, in order that the expected results to be relevant. Thus, the Romanit Lab was created, at the MNIR headquarters, which functioned with personnel under the direction of the Coordinator, together with two students from the Faculty of Geology (with a thesis in this field of activity), assisted by professors from UB. The purpose of the Romanit Lab is the primary study of the materials, as well as the information systematization regarding these materials. The Coordinator has distributed samples from the same "sources" to the analysts partners (I.4 and 5), as the resulted data set to actually be referential.
The research programme proposed for the three years of activity assumes operating with several hundreds of archaeological pieces, with other unprocessed amber sources, with thousands of samples and with several expertises. The correct management of this significant information set has represented one of the major pursuits of this beginning period.
- The ROMANIT data-base has been projected in this scope, operating on the following segments:
- A. The evidence of the archaeological pieces proposed for the project progress; this is performed within a typical "catalog" scheme, including illustration; this is the "inventory" segment (see Fig. 1)
- B. The inventory objects are, most of the time, beads comprising several pieces, often of different nature; the individual management of each studied object, individually, is performed on the "detail" informational segment (see Fig. 1, bottom, namely Fig. 2, where it is illustrated the collimation capacity of the information and of a certain photographic detail);
- C. Establishing an hierarchy for the objects that make the object of laboratory analyze, following the subsequent scheme:
- C.1 = "source" is an object that may represent an interest for the laboratory analyze, albeit it is an archaeological object (suitable for "detail" segment), or a geological reference object (see Table 1)
- C.2 = "sample" is a part of a "source", separated through prelevation, designated to one or more partners; the possibility of using a sample for multiple measurements or even for multiple partners results from the fact that certain analyses (such as FTIR, reflectance variant or difractometry) do no require material consumption, and other suppose a very modest consumption (1 mg for FTIR, pellets variant); technically, a "source" may be a "sample" with zero prelevation availability (Table 2), namely not suitable for prelevation;
- C.3 = "expertise" represents an analyze certificate or any other expertise form (macro and microscopic investigation) from which it results an opinion that leads to a conclusion (such as "sample X is, very probably, Baltic amber"); due to the fact that a sample may be used for several analyses, we have situations in which a "sample" represents the material for carrying out several "expertises"; the ideal situation corresponds to the verification of a scientific opinion with an opinion independently obtained, but the applicability is limited by the size of the samples that may be prelevated (Table 3).
These are the notions used not only in the data-base, but in this report as well.
for bibliographic references, see Resources > Bibliography
Eugenia Iamandei, Stănilă Iamandei
Amber (succinite or "ambra") appears as a very light and soft "stone", having an organic nature!
The name of ambra comes from Arabic, "al anbar" meaning golden yellow.
Succinite comes from Latine and might be translated by "(pine) sap".
Amber designation comes from Turkish language, "chiaruba" meaning "straw attracting", due to its property to electrify. For the same reasons, in Greek it was called "electronum", word from which it derives, not at all randomly, the modern word "electricity".
The romanite (> German rumänit) sin. moldavite = Romanian amber from Buzau county. The designation was proposed by Otto Helm (1891) after he observed chemical differences between the samples from Buzau area and those from the Baltic regions. The age of the amber strata deposits: Lower Oligocene.
From the mineralogical point of view, amber represents an organic compound with a very low hardness (app 2.5 on Mohs scale), which seems to be correlated with the transparency grade: the highest hardness represents the most transparent variety.
The color of amber may be very different: ice-like transparency, milky-white, yellow, pink-yellowish, yellow-greenish, cherry and even opaque-black. Opaline blue amber represents a rarity. Likewise, there is ardent orange, cream and black amber. Other colors: honey-like yellow, transparent or opaque, pure or having red inclusions, up to orange. Sometimes, it contains bubbles of air, small animals, insects, branches of fir tree, goldilocks germs, having thus violet, black, blue, red or green color. For example, Romanian amber from Colti-Buzau (the "romanite") has mainly dark colors, from red to black.
The chemical formula is, generally, C10H160, but minimum 24 elements may be comprised in its composition.
It has been formed, most probably, through the fossilization of resins coming from certain species of arboreal plants, coniferous and/ or angiosperm.
In Europe, it may be found in Baltic area, in Poland, Norway, Romania, Spain and across the seas, in Libya, China, Mexico, Nicaragua, Dominican Republic, Chile and other countries.
Considered more than 100 years as a distinct amber specie, romanite is now considered to be very similar to succinite (Stout et al. 2000), and seems to have a similar botanical origin. Through gas chromatography - mass spectrometry (GS-MS) it has been proved that romanite is "a succinite that suffered a partial thermal degradation during the tectonic events which lead to the formation of Kliwa sandstone folding, where the above-mention amber type may be found".
- Recurrences and supposed origins
There are, in literature, localizations of the source-areas, although most of the time fragmentary and imprecise. The precise localizations are, nevertheless, kept secret. For example, in France are approximately 32 occurrences, numerous in the Baltic countries, in Poland, in Germany, and in Romania there are app 400 denudations. The maps point out the geographical distribution of the occurrences. We also have a stratigraphical distribution (Geirnaert 2002).
Occurrences may appear in the sedimentary basins in which lignite surfaces. The biggest and most interesting samples have been found in such lignite strata.
The oldest deposits appear in the triasic from the Italian Alps, but resins traces also exists in the Carboniferous coal deposits.
In Romania we have fossil resins accumulations in almost 40 areals situated in 50 localities (see map from Figure 7). Of these, 12 are situated in Buzau county, Colti commune being a reference area (see the sketch from Figure 8). The largest number of occurrences for amber may be found in the area of the Paleogenous flysch from the east of Carpathians, beginning from Bucovina and up to Ialomita Valley (Ghiurca, Vávra 1990).
Most of the time, the amber deposits appear in sands or in gravel, and also where appear "glaises grises" or in fossil thalwegs of river, sedimentary barrier basin, anastomosed fluvial canals, woodsy swamps (Amazonian amber, see Geirnaert 2002) or marine deltas (most of the known deposits from Europe).
In Baltic countries amber seems to come from Paliogenous sedimentary formations that have thickness of 5-6 meters. In other areas the thickness is smaller; in France, for example, is of several cm.
The idea that amber is a fossil resin bled by the conifer Pinus succinifera is a false one, although it is present in all the encyclopedias. We may say that it is a fossil oleoresin; André Criqui (1956) determines that this is a scientific term applied especially to the spruce, pine fluid vegetal secretions, in which resins can be found, seed, as well as oils, acids, terpenes. Fossil resins are usually slightly different from the original oleoresins, due to the fact that they are strengthened, through chemical transformations, through the elimination of liquids, etc.
Conwentz (1980) stated that app 5 species of pine might generate Baltic amber, for which he emitted a collective taxonomy named Pinus succinifera, re-examining the Pinus succinifera taxonomy created by Göppert (1936, see also Göppert, Berendt 1845). The taxonomy has been subsequently emendated also by Schubert (1961). It, nevertheless, remains an imaginary taxonomy.
Numerous authors have supposed as resin generating sources Cedrus sp. (Katinas, 1987), Taxoxylum electrochyton (Menge 1858, cited by Conwentz 1990), Agathis sp. (Langenheim, 1963; Beck, 1993), but without having a paloebotanical confirmation of the existence of the pines cited in connection with the amber occurrences.
Nonetheless, the botanic origin of Baltic amber, which would cover a period of time of 18 million years, is less probable to be attributed to a single taxon or to taxons belonging only to gymnosperms Larsson 1978, Grimaldi 1996, Ganzelewski 1997, Geirnaert 2002), and since the possible correspondent oleoresins indicate angiospermic affinities (possible of Arecaceae, Quercineae), as well as gymnospermic affinities (of Pinaceae, Cupressaceae), Baltic amber seems thus very heterogeneous as origin. For example, the presence of alpha-amirinic acid, characteristic to certain angiosperm species, it cannot be a systematic chemical contamination of the resins that had fossilized. It is very less probable to existed gymnosperms which produced this acid in other geological times.
The origin of tertiary amber which appears in France also seems heterogeneous, but Cretaceous amber has typical Araucanian affinities, as indicate the advanced researches through modern techniques (Waggoner 1994; Lambert et al. 1994-1996).
Other possible botanical sources for Cretaceous amber might seem to be such angyospemics: Cheirolepidiaceae for necomian amber from Libya (Azar, 2000); Taxodiaceae or Cupressaceae for albian amber from Birmania (Grimaldi, Agosti 2002); Pinaceae or Taxodiaceae for turonian amber from New Jersey (Grimaldi et al., 2000).
Nevertheless, it is excluded the Araucanian source of the originary tertiary fossil because is proved that after the end of Cretaceous neither taxon belonging to Araucanian family appears in the northern hemisphere. The lack of knowledge as regarding the evolution of the paleophytogeography has allowed incorrect assumptions concerning the origin of oleoresins which generated amber in different areas on Earth.
- The Paleontology of amber
Very often, in amber, appear preserved, among mineral inclusions or gas bubbles and vegetal fragments (leaves, flowers, wood pieces, pollen, fungi, bacteria), small animals or different insects: ants, flies, wasps, bees, hoppers, spiders, scorpions, and even frogs or lizards, but also birds' feathers or animal fur spring. Their identification sketches the image, even only fragmentary, of the original ecosystem. These creatures fossilize through mummification, thus tridimensional aspects with structure details in perfect shape preserve, including, some times, the original color.
- Pershability and conservation
Being very fragile, amber is perishable. Acid water, light, the granulation of sandy rocks where it might be found, the presence of oxygen, the presence of salt dissolved in secondary sediments, all of them alter the fossil resins from the strata. Moreover, amber is very easily destroyed from the primary deposits through fluvial erosion and, actually, the fossil resins are most of the time accumulated in secondary deposits, where conservation conditions are unfavorable.
It is well known that from the physico-chemical point of view, the transformation of oleoresins in amber is, basically, made in two stages: first of all, it implies a relatively rapid polymerization reaction (several years), followed by an extremely slow aging (several million years) under the influence of the geological conditions from the deposit.
The resin, originally in fluid form, is a very complex mixture of organic molecules impregnated cu volatile molecules. After the resin is fixed in the sediments, a first reaction determines the organic molecules to bound one to another, creating thus a regulated and uniform structure (polymerized), structure which strengthens and becomes resistant, but at the same time it captures as well the volatile molecules, emanating the attractive fragrance.
The gradual releasing of the volatile molecules, for million of years, means the "aging phase", determined by the deposit conditions (pressure, temperature). Interesting phenomena occur with the organic inclusions (animal or vegetal) and the polymerization of the organic molecules.
One of the romanite characteristics is that it generally appears altered, namely oxidated. The altered fragments, named as well "burnt" or "degenerated" fragments (Murgoci 1903) are red-brownish, friable, transparent or translucent and with numerous fissures in their mass. The oxidated amber fragments contain a "core" of unaltered amber. The oxidated amber presents fissures on its surface due to the growing sensibility towards water (Srebrodoloskii 1979, in Shashoua 2002); as a consequence of degradation, the surface is fragmented. Amber changes its color to dark by air exposing, even in museal conditions, due to the action of the oxygen and of the humidity. This phenomenon is called degradation and may be recognized because the color of the material changes to dark and it forms a coating on the outside, as a results of the C=C connections' oxidation, with the forming of peroxides, acids and esters. The reaction mechanisms that characterize this phenomenon are not fully comprehended.
Short history of Romanian amber
(Eugenia Iamandei, Stanila Iamandei)
- During the modern epoch, namely the XIXth century, take place the first local exploitations, superficially (Ghiurca 1999). At the same time, appear the first scientific accounts regarding the apparition of amber in Buzau county (Stefanescu 1890). The first studies are published on Colti amber, comparing it with Baltic amber, and with the definitions of romanite, scuccinite varieties (Helm 1891; Istrati 1895-1898).
- Gh. Munteanu-Murgoci establishes the first systematic study of amber and publishes a series of scientific papers in 1902, 1903, 1924, 1925 and even writes a thesis named "Succinite deposits from Romania. The monograph of a mineral from the country".
- After 1902 the systematic exploitation commences (under the coordination of Engineer D. Grigorescu) in Buzau country, between 1924-1935 the maximum production being of 67-130 kg/year (only in 1927 - from the Colti mines 158 kg of amber had been extracted).
- During the next period, begin studies concerning the amber deposits from Buzau county, but as well studies regarding other 360 amber emergences from Romania, and fossil insects trapped in Colti amber are described (lepidopterous, dipterous, spiders, ants, termites, mosquitoes, wasps, plant flees, pseudoscoprions, phalangidae, different maggots, as well as lichens vegetable remains, acicular leaves of conifers, pollen granules, etc.).
- In 1929, on the occasion of the XIVth International Congress of Agriculture, Eng. D. Grigorescu organizes at Istrita o large amber exhibition, with up to 160 color shades.
- In 1932, at Paris, a new Romanian exhibition surprises the entire world with its beauty. Engineer D. Grigorescu, the person that symbolize the golden era of Romanian amber (1927-1937), personally offers to Queen Mary of England, wife of George the Vth, an amber medallion with enclosed insects. Another interesting piece is Stalin's pipe, which has been manufactured from the same Grigorescu's amber.
- However, after 1937, the mines from Colti slowly cease to function. After this date, only the inhabitants from Colti and different foreign adventurers seek "the sun-stone" and in 1947 the mines are completely closed down, the communist regime "officially and definitely forbidding" the amber extraction in Romania.
- Even so, local exploitation still functioned, being more or less organized: in 1947-1950 there was an attempt of retaking the exploitation; exploitations were performed between 1950-1980, followed by exploitation between 1980-1983, but with very unsuccessful results (a total of 22 kg of amber, which have been almost completely substracted).
- Mineralogical-gemological scientific studies regarding Colti amber or amber from different regions from the country have been written by: Ghiurca et al. (1986-1999), describing even varieties such as schraufit from Vama, almaschit from Piatra Neamt, muntenite from Olanesti, telegdite from Sasciori, together with the romanite from Colti (Frunzescu, Banoiu 2004).
- Petrescu et al. (1989) wrote a paleobotanical and palynological study, identifying a series of vegetal remains, even fossilized wood (7 samples) which highlighted the presence of Sequoioxylon gypsaceum taxodiaceae, a lauraceus identified as Laurinoxylon murgoci, and an icacinaceous (Icacinoxylon sp.). Pollen granules conserved in amber indicate oaks and elms (Cupuliferoidaepollenites liblarensis, Ulmipollenites undulosus), but as well conifers. The indications lead towards mixed mesophytic forests - typical vegetations for the Carpathian Oligocene.
- An "Amber Museum" was established at Colti (in 1973), at the present functioning as a department of the Regional Museum Buzau. The main attraction of the collection (one of the most valuable from the world) is represented by a stone, weighting 1. 857 kg. The amber from Colti shows typical color shades: from opaque - black to black - green, black - yellow, black-pearlish to shiny yellow.
- The amber collection is unique in the country, and at the same time among the few from the world, comprising: rocks with amber, coarse amber, tools used for amber extraction and processing. Thus, among the particular objects we mention an amber piece of 1785 g., another amber piece of 1500 g., amber objects having different color shades, from transparent yellow to opaque black, or with multiple shades in a single object.
Amber is one of the most adequate substances for the interdisciplinary studies, considered, along the time, as healing stone, amulet, designing object, jewelry and object of study for complex scientific researches, including the geological ones. For the study of modern and especially of the fossil resins, the physical methods remain the most important investigation method. Up to the present, we do not know all the compounds comprised by the modern and fossil resins; nevertheless, the physical methods combined with the mineralogical, paleobotanical and paleoentomological studies allowed several hypothesis and theories regarding:
- the capacity of some chemical compounds to remain unmodified during geological time, and thus explaing why amber may be produced only from certain resinous species;
- the paleobotanical origin of amber;
- paleobotanical distribution of certain species able of producing amber making resins;
- physico-chemical modifications suffered by the resins during geological time;
- the action of diagenetic processes on the chemistry of resins and amber.
Firstly, the molecular structure of modern and fossil resins was deciphered. Due to the extremely complicated chemical composition of the resins, their chemical inaction, as well as their partial solubility in organic solvents, several analytical methods were used: infrared spectroscopy (IR), X-ray difractometry (RX), nuclear magnetic resonance (RMN), chromatography, mass and emission spectrometry, neutron activation, differentiate thermal analysis. As the investigation advanced, it was felt the need of redefining several terms which designated amber varieties, abandoning some of them on the basis of the new chemical-analytical and geological criteria.
Among the methods that inflicted in amber research, microscopy occupies a privileged place. Apart from efficiency and commodity, it offers a precision grade comparable only with the chemical analyses, and at the same time it allows the examination of the relations between mineral species, and, further on, the detailed investigation of the mineralogical composition of the resins, of the host-rock, being thus possible to assert genetic considerations, the paleobotanical origin of the bleeding arbor for amber and, at the same time, emphasizing paleoecological appreciations.
Moreover, the microscopically study allows the chemical and physical characterization of the different mineral phases, thus the reconstitution of the primary resins depositing phases.
The main aim of the future multidisciplinary studies will be to establish whether it is possible to establish if the romanite is an independent amber species, especially that the Polish researchers (Kosmowska-Ceranowicz, 1999) mention that on the basis of IR studies, some varieties of fossil resins may be assimilated to romanite, the differences being connected to the different geological ambiances where they have been preserved. Namely, we refer to the amber from Sahalin Island (sahalinite) and Caucasus Mountain ("Caucasian rumanite", in K2 deposits from Azerbadjan), to birmite, schraufit, delatynite, retinite from Trepcza (Poland) and Voronej region (Russia), and as well to Fushun amber (China) and some varieties of Japanese amber.
From the mineralogical point of view, amber is a mineraloid (Neacsu 2003), notion that designates amorphous or cryptocrystalline natural substances, with a chemical composition unsolved yet, and therefore that cannot be represented through a formula.
The main mineralogical characteristics of amber are shown in table 12. The determinations vary from sample to sample due to the extremely heterogeneous structure of the material (Savkevich, 1967).
Color is among the main characterization criteria of ambriferous: although the original resin is the same (succine), it develops, during geological time, particular characteristics, depending on the preservations conditions from its appearance moment until it reaches fluid state, going through successive remobilizations and redeposits, until its concentration in a certain geological ambiance.
The color of amber depends on the paleoclimatic and even paleontologic characteristics of the environment in which the primary resin is bled, and as well on the geological context in which the resin, already partially modified under the influence of under-aerial conditions, suffers the fossilization mechanisms.
As regards the romanite from Colti region, the color varies from yellow to red-brownish and black, with intermediary shades (see fig. 25). The color of romanite powder varies according to the fragments from which it comes and it maintains in light-yellow and reddish shades.
The frequent transparent varieties are yellow-brownish and brown-greenish.
The color changes in time, especially due to the action of oxygen and light on the resin.
Color is an important property for gemologists, the most valuable exemplars being considered the transparent-yellowish overcastted with white, if we refer to succinite (B. Kosmowska-Ceranowicz, at the opening of "Amber - from flowing resin to jewelry" exhibition, Antipa Museum 2003), the yellow-brownish shades if we refer to romanite, and the blue ones for Dominican amber. The color may be more or less radically changed through thermal processing industrial procedures, situation in which we can no longer refer to natural amber, but to "improved" amber, unfortunately chosen by most of the purchasers.
The trace of graze with a steel needle on the surface of amber is represented by a line with edges perfectly smooth.When touched, amber gives the feeling of warmth.
Turbulence is given by the presence of fluid inclusions (fig. 9) and of the succinic acid, being a measure of amber's transparency grade. The lesser the inclusions, with smaller dimensions and less dispersed in the mass of the resin, the more the chances for a transparent amber. If the primary amber has been exposed to heat for a longer time (under the action of sun-rays) the loss of volatile components is bigger and drastically, decreasing the turbulence and intensifying the transparency of the fossil resin. This is the case of romanite, where fluid inclusions in some samples may be observed. In such case, only relatively small portions are of interest. Likewise, the elimination of the volatiles and of the water led to the appearance of small fissures, but with distinct esthetic effects. The process has been radical in the case of romanite, observing at the microscope contraction fissures (fig. 10).
The fracture is conchoidal.
The gloss is resinous.
From the point of view of the romanite's transparency, it may be transparent, opaque or translucent. The transparency grade of amber is important in order to establish the processing modality (Ionescu 2001): the transparent one is side-processed, and if it is of dark color and with multiple inclusions, it is smooth-processed, likewise the transparent ones. The transparency is ameliorated by slow heating.
The presence of fluid inclusions reduces the transparency, especially if they are numerous, have small dimensions and are dispersed in the mass of the fossil resin.
The literature signals the transparency higher frequency apparition at romanite, towards the Baltic varieties, for example. We suppose that the influence of diagenese explains the transparency emphasis at the Colti area amber.
Amber is partially solvable in solvents (table 13). The oxidation due to under-air exposure creases the solubility, especially in polar solvents (Shashoua 2002).
The specific weight varies, with approximation, between 1.05 and 1.10 g/ cm3. Amber floats in saline saturated solution, unlike the majority of stimulants (for example, plastic materials),which sink. The specific weight creases from the inferior varieties, from the gemological point of view, to transparent amber (Shashoua 2002). The specific weight creases with approximately 15-40% after oxidation (Savkevich 1967, in Shashoua 2002).
Amber is combustible (introduced in flame it produces a small blaze and emanates a black fume). The smell is of incense.
Although in literature is highlighted the fact that amber does not present crystallization tendencies (Kucharska, Kwiatkowski 1977, Stout et al. 1995), the microscopic study on thin sections of romanite allowed the emphasizing of a light anisotropy:
Anisotropy colors vary from grey- yellowish to light-blue (fig. 11). The observations have been marked up at the Faculty of Geology and Geophysics, Economic Metalogeny and Geology Laboratory, using a PANPHOT microscope transmitted light, to which a Nikon Eclipse E-400, 40 W has been attached, being thus possible to obtain microscopical images. The thin sections have been manufactured at the Sections' Laboratory from the Mineralogy Department, from romanite and Baltic amber (table 14).
The complexity of the internal structure of romanite "is due, probably, to the tectonic stress provoked on the ambriferous argillaceous levels, more plastic than sandstone with which they alternate, associated with relative high temperatures, provoking thus the partial elimination of the volatile substances, of the water and of the air from the fossil resin" (Ghiurca 1997), determining therefore an intern reorganization until the individualization of certain crystals, as it is showed by the RX difractograms on Colti romanite (Neacsu 2003). Another important consequence is the brightness intensification, which transformed the translucent varieties in transparent varieties.
Having a novelty character, is the obvious presence on sections of two different romanite types: an older one, with distinct fissures, impregnated with organic material, and a recent one, lighter, which borders the previous one and penetrates its fissures (fig. 12); we can mention two different internal reorganization grades (incipient crystallization tendency), more accentuated at the older romanite, that has a pronounced anisotropy (fig. 13). Likewise, as a working hypothesis, we highlight the anisotropy tendency especially in the presence of organic material (fig. 14).
Baltic amber studied with this occasion revealed no anisotropy, except for the fact that a certain circular zonation of the inclusions' disposal may be observed, highlighting that in the space in which the inclusions are less frequent, seem to be a very light anisotropy (fig. 9).
The microscopic study of romanite emphasized the presence of pollen (Dragastan et al. 1980) of Sequoiapollenites type? from the European tertiary, (fig. 15), of spores (of Osmundaceae?) (fig. 16), and of wood vessels remains, free, cortex, all of them comprised by the resin (fig. 17).
Ligneous texture may be observed in the sections from Baltic amber, included in the resin, as well as organic texture substituted by resin (amber pseudomorphosis after the organic texture, fig. 19).
The microscopic study of amber revealed the surprise of identification certain paleofossils from Insecta class, Coleoptera order (fig. 20) in Baltic amber, and from Arachnida class, Pseudoscorpiones F1 order in romanite.
From what is known up to the present, in romanite, the remains of fossil organisms are rare comparing to Baltic succinite (where the probability to find samples is of 1/ 1000) or to Dominican amber (1/ 100). The main causes seem to be:
- the generally reduced sizes of ambriferous fragments;
- the higher intensity of the alteration and fossilization processes which affected the resin from which the romanite was formed, processes that might have acted on the organic substance, transforming it in simpler compounds (the loss of water, the frequency of simple C-H relations type and the -COOH groupings attested by the IR and FTIR spectroscopy, see Neacsu 2003);
- the depositing conditions have been different than the ones from other areas of the Globe. It's worth mentioning the diagenesis effects.
- Romanite is, usually, transparent, which means that:
- the fluid inclusions had time to be emitted, due to a longer exposure to sunlight, or to the influence of the temperature during the diagenesis;
- the fluid inclusions have a lower dispersion level;
- even this microscopic study allowed the highlighting of certain albite inclusions of neo-formation in romanite, surrounded by albite idiomorphous crystals, of small dimensions (fig. 22), remineralizations of anhydritization and albitization type (fig. 23), the anisotropization process at romanite (fig. 11, 13), all of them being the effect of diagenesis;
- the superior maturation grade of romanite, unlike Baltic amber, is also an effect of diagenesis and of the conditions from the preservation environment;
- micro-fissures apparition (photo 31F1, 4F2 - fig. 10) as a results of water and volatiles drastic elimination;
- the lack of fossil resins may be an indication for a poorer fauna, as it might be supposed for the sandy shores of the oligocenous sea.
The inclusions of fossil wood in romanite, considered to be of Oligocenous age (32.5-22.5 millions of years, see Ghiurca 1996) are attributed to Sequoioxylon gypsaceum (Petrescu et al. 1989), considered as the main "producer" of resin found on the territory of Romania. Sequoioxylon belonged to a delta-lagoon type of environment, with a sub-tropical climate (Ghiurca et al. 1986).
As a general conclusion, it's worth retaining Savkevich's hypothesis (1980, after Kosmowska-Ceranowicz 1999), according to which gedanite transforms, during geological time, in succinite and then in romanite. The later transformation is determined by the modifications induced by the diagenesis and by the metamorphism processes which played a significant role in the formation of romanite. Thus, the romanite might be the last link in the evolution process of the fossil resin for amber. Considering that the geographical distribution of succinite don't include the area from the south of the Alpes (Savkevich 1981), being thus distinctively separated by the geographic distribution of the romanite (even if we accept the expansion of the term beyond the Romanian territory), we must take into consideration the hypothesis that it existed, during the formation process of the amber resins, a gedanite phase, which evolved then in succinite and, depending on the geo-chemical context, further on in romanite.