Murat Hatipoğlu

Natural carbon black (Oltu-stone) from Turkey: a micro-Raman study

This study focuses on the characterization of a carbon black material from the Oltu-Erzurum region (traditionally called in Turkey “Oltu-stone” or “black-amber”), which is of interest in several fi elds, among these archaeometry and jewellery. Raman spectra were recorded between 50 and 3200 cm−1: measurements in a wide spectral range are the basis for effective characterization and identifi cation with respect to analogous materials. Correlations between the spectrum and the structure are discussed: two higher energetic Raman peaks at 1346 and 1585 cm–1 are characteristic of the crystalline carbon regions, whereas the weaker ones at 2654 and 2904 cm–1 are ascribed to amorphous carbon regions on the Oltu-stone surface. In addition, the enhanced background between 250 and 400 cm–1 could be associated with the presence of pyrite.

Spectral, electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balıkesir region of Turkey

Amethyst crystals on matrix specimens from the Dursunbey-Balıkesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675 nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760 nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50 ppm), Co (3.1 ppm), Ni (38 ppm), Cu (17.9 ppm), Zn (10 ppm), Zr (3.9 ppm), and Mo (21.8 ppm).

Gemstone Deposits in Turkey

is not known as a producer of gemstones. In this article, we summarize six deposits: diaspore, fire opal, blue chalcedony, amethyst, smoky quartz, and agate. Close scrutiny of a recent compendium of mineral localities (Bernard and Hyrsl 2004) shows that only gem diaspore is recognized as coming from Turkey and then only in the past decade or so. Current commercial sources of amethyst include Uruguay, Brazil, Zambia, Mozambique, Mexico, and Siberia. Fire opal is commercially available from Mexico and Brazil. Smoky quartz is available from numerous sources including Brazil, Madagascar, Russia, Scotland, Switzerland, and Ukraine. Blue chalcedony for gemstone use is produced in Nevada (Mount Airy blue), California (Mohave blue), and Namibia (African blue). Commercial production of agates is geographically widespread and includes Brazil, Mexico, Botswana, Australia, Argentina, and the United States (Minnesota, Montana, and South Dakota), but not Turkey. In fact, significant deposits of all six of these gemstones occur in Turkey. As shown in figure 1, Turkey comprises the Anatolian plate, which is wedged between much larger tectonic plates, including the African plate, the Arabian plate, the Black Sea plate, and the Aegean plate. These plates have been actively moving at least since the Paleocene (65 million years ago [mya]). As a result, Turkey experiences frequent, often serious earthquakes (Tan, Tapirdamaz, and Yörük 2008), such as the pair of deadly quakes that occurred in 1999 along the North Anatolian Fault Zone (NAF, fig. 1). Generally, the gemstone occurrences described here are found in Gemstone Deposits

Amethyst and morion quartz gemstone raw materials from Turkey: color saturation and enhancement by gamma, neutron and beta irradiation

Color-enhancement investigations without using heating treatment from dull or pale to ideal saturation and/or changes to the formation of the rarer attractive colors are widely conducted to revalue abandoned gem material sources in the world. Such an investigation is carried out on pale or dull purple-colored amethyst and smoky-colored morion samples, which are two important gem species of the crystalline quartz (SiO2) mineral that are currently abandoned in natural deposits in Turkey because of their unattractive coloration. The results of color enhancements observed on these samples, after irradiation with artificial gamma, neutron and beta beams, were examined by comparing with samples with the ideal color saturation and also with colorless samples, using optical absorption (OA) and radioluminescence (RL) spectroscopy. The ICP-AES analyses reveal that the main impurity elements of over 100 ppm in abundance in these quartz species are aluminum, iron and titanium for amethyst, and aluminum, iron, titanium and manganese for morion. The OA spectra indicate that vivid purple coloration of amethyst is due to the transmittance at about 395–420 nm band gap as a result of absorbance peaks at 375, 480 and 530 nm. These absorbances may be related to the unusual oxidized small proportions of certain impurity ions, after being exposed mainly to gamma irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Fe(IV) from the total iron, respectively. However, the RL spectroscopy of amethyst samples before and after they were exposed to artificial gamma, neutron and beta radiation beams demonstrates that the ions most affected by irradiation are Fe(IV) first and Al(IV) and Ti(V) second, and these ions represent the RL peaks at 600, 720 and 495 nm, respectively. The OA spectra indicate that dark smoky coloration in morion is due to a lack of transmittance at the visible region as a result of the absorbance peaks at 375, 450–490, 620 and 730 nm. These absorbances also may be related to the unusual oxidized small proportions of certain impurity ions by irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Mn(III) from the total manganese, respectively. In addition, the buoyancies of these absorbance peaks in the visible region produce the color hues between light smoky and dark smoky colorations in morion samples. These oxidized ion states are more resistant and stable against environmental destructive conditions in comparison with amethyst. Thus, the dark smoky coloration of morion becomes dull or pale after relatively longer periods. But, the RL spectroscopy of morion before and after being exposed to gamma, neutron and beta irradiation beams demonstrates that the most induced ions from the irradiation are Mn(III) and Al(IV) first and Ti(V) second. These ions represent the RL peaks at about 400, 720 and about 500 nm, respectively.

The first Glyptostroboxylon from the Miocene of Turkey

Silicified wood preserved in the Gudul fossil forest site in the Galatian Volcanic Province (GVP) near Ankara in Central Anatolia is described. The material comprises six petrified wood samples that date from early to middle Miocene. The woods have very low rays (2–5 cells high), bordered tracheidal pitting (9–10 μm), pinoid cross-field pits and very thin, unpitted, smooth walls of axial parenchyma and rays. This combination of characters indicates affinity to the fossil-genus Glyptostroboxylon. The presence of this wood genus suggests that the local environment was either riparian or wetland forest.

Photoluminescence Response from the Turkish Dentritic Agates

The three-dimensional photoluminescence emissions between 380 and 800 nm of the dentritic agate with white body color from the Dereyalak-İnönü-Eskişehir (Turkey) region were obtained at the temperatures between 250 and 340 K under 366 nm excitation. The most advantage of three-dimensional photoluminescence graphic in a silica structure is to demonstrate clearly all vibronic structures through temperature increasing on the spectra. Hence, photoluminescence response from the gem-quality material was discussed in relation to chemical impurities of trivalent rare earth elements. In the photoluminescence spectra, two strong and many weaker emission bands became clear at the lower temperature (250 K) conditions. First strong one is the purple band, and the highest emission peak is observed at 394 nm. Second strong one is the red band, and the highest emission peak is observed at 717 nm. The half-width of these main bands is approximately 17–19 nm, and such bands combination is typical for trivalent rare earth elements. Chemical analyses in this study show the abundances of many rare earth elements in the material. In order of abundance, they are yttrium (845 ppm), gadolinium (238 ppm), lutetium (196 ppm), dysprosium (45 ppm), neodymium (41 ppm), promethium (34 ppm), europium (18 ppm), and scandium (3 ppm). However, the two strong emission bands are, of course, due to yttrium and gadolinium ions, respectively. As a result, the intensities of these bands gradually decreased forming a sequence until the temperature of 280 K. Hence, the photoluminescence of the Turkish dentritic agates does not exist at higher temperatures, mainly because of high iron (40.000 ppm) abundance.

Photoluminescence Response from the Chromian Clinochlore (Kammererite)

ABSTRACT The three-dimensional photoluminescence emissions between 450 and 800 nm of kammererite from Turkey were obtained at the temperatures between 230 and 350 K under 366 nm excitation. The most advantage of three-dimensional photoluminescence is to demonstrate clearly all vibronic structures through temperature increasing on the spectra. Hence, photoluminescence response from the unique gem material was discussed in relation to chemical impurities. In the photoluminescence spectra, two strong and three weaker emission bands became clear at the lower temperature conditions. First strong green band with the highest emission peak at 545 nm, and second strong yellowish-orange band with the highest emission peak at 610 nm were observed at 230 K. The half-width of the main bands is approximately 10–12 nm and such bands combination is typical for trivalent rare-earth elements. These two strong emission bands are due to europium and gadolinium ions, respectively. In addition, the weaker emission bands at 485, 585, and 615 nm were detected at mainly 230 K. The bands peaked at 485 was attributed to lanthanum, lutetium, promethium, scandium, and yttrium centers, and 585 nm was attributed to dysprosium center. Since, the abundances of these rare-earth elements produced relatively strong luminescence bands in the spectra. Finally, the weakest band peaked at 615 nm was attributed to neodymium. As a result, the intensities of these bands gradually decreased forming a sequence until the temperature of 280 K. The lanthanum is the main responsible ion that extinguishes the photoluminescence at the relatively higher temperature conditions in the minerals. Therefore, the photoluminescence of kammererite exists at low temperatures only, because of mainly high lanthanum (90 ppm) abundance.

Comparative Fourier Transform Infrared Investigation of Oltu-Stone (Natural Carbon Black) and Jet

ABSTRACT Fourier transform infrared (FT-IR) investigation of Oltu-stone (natural carbon black) and jet revealed several differences between these carbonaceous materials. The band peaking at about 1000 cm−1 is the first important difference: while the band in the jet spectra appears as one sharp peak at about 1001 cm−1, the similar band in the Oltu-stone spectra is shifted to about 1026 cm−1 with a broad shoulder toward high frequency. Even though the assignment of the shifted band is at present controversial, it may be attributed to carbon-oxygen stretching mode. Second, the doublet bands at about 2912 and 2843 cm−1 are much more intense in the jet spectra then in the Oltu-stone spectra. They are confidently attributed to aliphatic C-H stretching mode. Finally, the broad water band on setting at about 3750 cm−1 is maturated in Oltu-stone, and it is much more evident than in that of jet. Therefore, FT-IR appears as a favorable identification method for these kinds of carbonaceous materials.

A Gem Diaspore Occurrence near Pinarcik, Mugla, Turkey

Diaspore has generally not been a popular mineral with collectors. Aside from several classic localities such as the nepheline-syenite pegmatites at Ovre Åro, Norway, the emery schists at Mramorskoi in the Russian Urals, and the marbles at Campolongo, Switzerland, displayable diaspore specimens have been few and far between. Collectors of American classics will be familiar with the fawn-colored prismatic crystals from Corundum Hill, Newlin Township, Chester County, Pennsylvania, or the lavender tabular crystals from the emery mines near Chester, Hampden County, Massachusetts. Diaspore is most commonly, with gibbsite and boehmite, a main constituent of metamorphosed bauxite deposits (diasporites) (Gordon, Tracey, and near Pinarcik, Mugla, Turkey A Gem Diaspore Occurrence

Lapeyreite, Cu3O[AsO3(OH)]2·0.75H2O, a new mineral: Its description and crystal structure

Abstract Lapeyreite, ideally Cu3O[AsO3(OH)]2⋅0.75H2O, was found in the old copper mines of Roua (Alpes-Maritimes, France). It is invariably in intimate association with trippkeite. Other associated minerals are olivenite, malachite, gilmarite, cornubite, connellite, theoparacelsite, brochantite, cuprite, native copper, algodonite, and domeykite. Lapeyreite occurs in geodes of cuprite (0.5 mm diameter) as aggregates formed by perfect elongate rectangular crystals (up to 0.2 × 0.05 × 0.01 mm in size), acicular fibrous crystals or powdery masses. The mineral is translucent (transparent in thin fragments), dark pistachio-green. It has a vitreous to adamantine luster and yellowish green streak. The tenacity is brittle and the fracture conchoidal. The rectangular crystals are elongate parallel to [010], flattened on (001), and have a perfect cleavage on {001}, and good cleavage on {100}. All crystals, without exception, are twinned on the (001) plane. The recognizable crystal forms are {100}, {010}, and {001}. In transmitted light, the mineral is pistachio-green, with strong pleochroism: X = light yellow-green, Y = pistachio-green, Z = dark pistachio-green; dispersion: r > v, medium. Lapeyreite is biaxial (+), with nα ~ 1.82, nβ ~ 1.85, nγ ~ 1.90 (for λ = 589 nm). 2Vmeas = 76° (universal stage), 2Vcalc = 77°. The optical orientation is X ^ c ~ 12°, Y = a, Z = b. The mean chemical composition determined by electron microprobe is (wt%): CuO 46.49, As2O5 45.82, H2O (from crystal structure analysis) 6.30, total 98.61. The empirical formula calculated on the basis of nine structural O atoms (excluding molecular water) is Cu2.96As2.01O6.99(OH)2.01⋅0.77H2O. Lapeyreite is monoclinic, C2/m, a = 19.158(3), b = 2.9361(6), c = 9.193(2) Å, β = 103.26(1)°, V = 503.32(6) Å3, Z = 8/3. The calculated density is 4.385 g/cm3 (based on the empirical formula). The strongest X-ray powder-diffraction lines are [d(Å) (I) (hkl)]: 7.36 (30) (2̅01), 5.842 (40) (201), 4.476 (35) (002), 3.173 (90) (6̅01), 2.984 (100) (003), 2.883 (30) (6̅02), 2.484 (80) (311), 2.396 (40) (112, 8̅01), and 2.337 (35) (800). The crystal structure of lapeyreite was solved by direct methods (MoKα radiation) and refined on F2 using all 617 observed reflections to R = 0.069. The structure of lapeyreite is formed by a three-dimensional network of CuO5 square pyramids and AsO4 tetrahedra with a water molecule in structural cavities. This structure shows some similarities to that of theoparacelsite. The mineral is named in honor of Laurent Lapeyre, an eminent mineral collector and expert on Roua minerals.