### Introduction

Earth’s carbon, derived from planetesimals in the 1 AU region during accretion of the Solar System, still retains similarities to carbon found in meteorites (Marty et al. 2013) even after 4.57 billion years of geological processing. The range in isotopic composition of carbon on Earth versus meteorites is nearly identical and, for both, diamond is a common, if volumetrically minor, carbon mineral (Haggerty 1999). Diamond is one of the three native carbon minerals on Earth (the other two being graphite and lonsdaleite). It can crystallize throughout the mantle below about 150 km and can occur metastably in the crust. Diamond is a rare mineral, occurring at the part-per-billion level even within the most diamondiferous volcanic host rock although some rare eclogites have been known to contain 10–15% diamond. As a trace mineral it is unevenly distributed and, except for occurrences in metamorphosed crustal rocks, it is a xenocrystic phase within the series of volcanic rocks (kimberlites, lamproites, ultramafic lamprohyres), which bring it to the surface and host it. The occurrence of diamond on Earth’s surface results from its unique resistance to alteration/dissolution and the sometimes accidental circumstances of its sampling by the volcanic host rock. Diamonds are usually the chief minerals left from their depth of formation, because intact diamondiferous mantle xenoliths are rare.

Diamond has been intensively studied over the last 40 years to provide extraordinary information on our planet’s interior. For example, from the study of its inclusions, diamond is recognized as the only material sampling the “very deep” mantle to depths exceeding 800 km (Harte et al. 1999; McCammon 2001; Stachel and Harris 2009; Harte 2010) although most crystals (~95%) derive from shallower depths (150 to 250 km). Diamonds are less useful in determining carbon fluxes on Earth because they provide only a small, …

Diamonds and the Geology of Mantle Carbon

### Dashkovaite*

N.V. Chukanov, D.I. Belakovsky, S.V. Malinko, N.I. Organova (2000) Dashkovaite Mg(HCO3)2·2H2O — A new formate mineral. Zapiski Vseross. Mineral. Obshch., 129(6), 49–53 (in Russian, English abs.).

Chemical analysis gave C 16.2, H 3.9, Mg 16.4, Mn (by electron microprobe) 0.2, O (by difference) 63.3, sum 100 wt%, corresponding to Mg1.00Mn0.01H5.74C2.00O5.87, ideally Mg(HCO3)2 2H2O. The mineral occurs as white, fibrous aggregates in hydrothermal veinlets, up to 1 mm in width, wherein the fibers are up to 3 mm long and 0.01 mm wide. Soft and porous, H = 1, D calc = 1.74 g/cm3 for Z = 4. Microscopically colorless, biaxial positive, α = 1.465(3), α = 1.486(3), γ = 1.516(3), 2 V calc = 81(5)°, X parallel to the elongation. By analogy with the synthetic analog, indexing of the X-ray powder pattern gave a monoclinic cell, space group P 21/ c , a = 8.64(1), b = 7.15(1), c = 9.38(1) A, α = 98.0(1) °; strongest lines of the pattern (57 mm camera, Fe K α radiation) are 4.90(90,111), 4.64(80,002), 4.30(70,200), 3.68(80,210), and 3.40(100,112). The IR spectrum is similar to that of the synthetic compound.

The mineral occurs with shabynite, iowaite, ekaterinite, korshunovskite, halite, hydromagnesite, and serpentine in dolomite marble at the Korshunovskoye boron deposit in the Irkutsk district, Siberia. The new mineral name is for E.R. Dashkova (1744–1810), former Director of the Saint Petersburg Academy of Sciences (1783–1796) and President of the Russian Academy of Sciences. Type material is in the Fersman Mineralogical Museum, Moscow, Russia. J.L.J. 

### Fluorannite*

Ganfu Shen, Qi Lu, Jinsha Xu (2000) Fluorannite: A new mineral of the mica group from the western suburb of Suzhou City. Acta Petrologica Mineral., 19(4), 355–362 …

New mineral names

Phase Transitions in Ferroelastic and Co-Elastic Crystals

Diamonds and other ultrahigh pressure (UHP) minerals have been reported previously from the Luobusa ophiolite of Tibet, but these minerals have thus far been found only as individual grains. Here we report the occurrence of diamond as an inclusion in OsIr alloy and coesite as part of a silicate assemblage rimming a grain of FeTi alloy, both of which were recovered from chromitite. These occurrences confirm the presence of UHP minerals in the Luobusa chromitite requiring minimum pressures of ∼2.8–4 GPa. Individual coesite “crystals” have external form similar to that of stishovite and are polycrystalline, suggesting pseudo morphic replacement and implying a pressure >9 GPa. We propose that the UHP minerals were incorporated into the chromitites in the deep upper mantle or that they have an impact origin; the preponderance of evidence favors the former.

Diamond- and coesite-bearing chromitites from the Luobusa ophiolite, Tibet

The microcrystals of monoclinic europium molybdate, α-Eu2(MoO4)3, have been fabricated by solid-state synthesis at T = 753–1273 K for 300 h. The crystal structure of α-Eu2(MoO4)3 has been refined by the Rietveld method and was found to belong to the space group C2/c with unit cell parameters a = 7.5576(1), b = 11.4709(2), c = 11.5158(2) A, and β = 109.278(1)° (RB = 3.39%). About 40 narrow Raman lines have been observed in the Raman spectrum of the α-Eu2(MoO4)3 powder sample. The luminescence spectra of α-Eu2(MoO4)3 under excitation at 355 and 457.9 nm reveal domination of induced electric dipole transition 5D0 → 7F2 and the presence of ultranarrow lines at 5D0 → 7F0 and 5D1 → 7F0 transitions.

Synthesis and Spectroscopic Properties of Monoclinic α-Eu2(MoO4)3

Mineral inclusions in diamonds provide an important source of information about the composition of the continental lithosphere at depths exceeding 120–150 km, i.e., within the diamond stability field. Fossilized high pressures in coesite inclusions from a Venezuela diamond have been identified and measured by using laser Raman and synchrotron x-ray microanalytical techniques. Micro-Raman measurements on an intact inclusion of remnant vibrational band shifts give a high confining pressure of 3.62 (±0.18) GPa. Synchrotron single-crystal diffraction measurements of the volume compression are in accord with the Raman results and also revealed direct structural information on the state of the inclusion. In contrast to olivine and garnet inclusions, the thermoelasticity of coesite favors accurate identification of pressure preservation. Owing to the unique combination of physical properties of coesite and diamond, this “coesite-in-diamond” geobarometer is virtually independent of temperature, allowing an estimation of the initial pressure of Venezuela diamond formation of 5.5 (±0.5) GPa.

https://www.pnas.org/content/pnas/97/22/11875.full.pdf

Fossilized high pressure from the Earth's deep interior: The coesite-in-diamond barometer

The water tracer diffusion in single crystals of natrolite, scolecite, mesolite, heulandite, and chabazite has been studied by Raman micro-spectroscopy. A model of water tracer diffusion is proposed. The H2O, HDO, and D2O molecule concentrations are calculated for a crystal of orthorhombic symmetry on deuteration of the initial H2O-sample. A way is shown to find the diffusion coefficients, the constant of equilibrium, and the deuteron-proton exchange rate from experimental data. The water diffusion coefficients for natrolite placed in liquid D2O appeared to be 1.5–2 times higher than those for a sample in vaporous D2O. For natrolite at room temperature, 1.5–1.6 times higher water diffusion occurs along [001] than along [110].

Raman Spectroscopy of Water Tracer Diffusion in Zeolite Single Crystals

Micro-Raman spectroscopy and X-ray diffraction method (XRD) were used to characterize impact carbonaceous rocks excavated from the Popigai crater (Siberia). The deconvolution of the first-order Raman spectra of the rocks containing different amounts of carbon phases (diamond, lonsdaleite and graphite) allowed the identification of lonsdaleite spectrum. The most intensive band at 1292–1303 cm−1 was ascribed to A1g vibration mode of lonsdaleite, whereas the less intense band at 1219–1244 cm−1 was attributed, in agreement with previously reported ab initio calculations, to E2g vibration mode. The established correlation between the intensities of Raman and XRD peaks permits a rough estimation of lonsdaleite/diamond phase ratio in the impact rocks using micro-Raman measurements. The second-order Raman spectra of lonsdaleite–diamond rocks were recorded. Copyright © 2014 John Wiley & Sons, Ltd.

Raman identification of lonsdaleite in Popigai impactites

Tululite (Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 (the hypothetical end-member formula Ca14{Fe3+O6}[SiO4][Zn5Al9]O26) (IMA2014-065) is a new natural Ca zincate-aluminate, identified in medium-temperature (800–850 °C) combustion metamorphic (CM) spurrite-fluorellestadite marbles from central Jordan. The type locality (Tulul Al Hammam area) is situated in the northern part of the Siwaqa complex, the largest area of the “Mottled Zone” Formation in the Dead Sea region. The marbles originated from bitumen-rich chalky marine sediments of the Maastrichtian-Paleogene Muwaqqar Chalk Marl Formation, which have low clay content (and, consequently, low Al) and high Zn, Cd, and U enrichments. The bulk CM rocks derived from the low-Al protolith have unusually high (Zn + Cd)/Al ratios (~0.2) and, as a result, a mineralogy with negligibly small percentages of Ca aluminates having low Ca:Al molar ratios (minerals of mayenite supergroup, Ca:Al = 6:7) common to most of calcareous CM rocks in the Mottled Zone. Instead, the mineral assemblage of the Zn-rich marbles contains tululite, with high Ca:Al = 2.55 molar ratios and Zn substituting for a large portion of Al (Zn:Al = 1.1). Tululite occurs in thin clusters as irregular grains with indented outlines (20–100 μm in size), having typical open-work textures associated with rock-forming calcite, fluorellestadite, spurrite, and accessory Zn-rich periclase, lime-monteponite solid solutions, calcium uranates, and zincite. Marbles also bear brownmillerite, dorrite, fluormayenite, high-fluorine Ca aluminate, and lakargiite. Secondary phases are brucite, gel-like calcium silicate hydrates and calcium silicate aluminate hydrates, including Zn- and U-bearing and Cd-rich compounds, Si-bearing hydrated compounds after calcium uranates, and basic Cd chlorides. The empirical formula of the holotype tululite (a mean of 32 analyses) is (Ca13.29Cd0.75)Σ14.04(Al5.46Zn5.20Fe3+
 2.23Si0.95Mn3+
 1.01Mg0.78P0.41)Σ16.04O36. Tululite is cubic, space group F23; a = 14.9346(4) A; V = 3331.07(15) A3, Z = 4. The strongest lines of the X-ray powder-diffraction pattern [d, A – (I
 obs
 )] are: 2.874(57), 2.640 (100), 2.524(42), 2.278(41), 1.760(54), 1.725(25), 1.524(33), 1.500(33). The crystal structure was solved from single-crystal X-ray diffraction data and refined to wR2 = 0.0672 on the basis of 913 unique reflections with I
 0
  > 2σ(I). Tululite belongs to a group of compounds with the general formula Ca14
 MT
 15O35+x
 (0 ≤ x ≤ 1), and is a new structure type. The tetrahedral framework of tululite structure is formed by T7O13 secondary building units (SBU), which consist of four corner-linked tetrahedra sharing a common oxygen atom and three tetrahedra sharing two O atoms with the neighbor SBU. Ca2+ cations occupy three positions; two of them also contain a minor amount of Cd2+. The Ca sites surround an island (Fe3+,Al)O6 octahedron and a (Si,P)O4 tetrahedron in the centers of framework cages at the junction of eight SBUs. The (Fe3+,Al)O6 octahedron is coordinated by fourteen Ca positions into a 6-capped cube, whereas the (Si,P)O4 tetrahedron is coordinated by six Ca positions into a regular octahedron. The structural formula of tululite is Ca14{Fe3+O6}M1[(Si,P)O4]T1[(Al,Zn)7O13]2
 T2-T4. The mineral is yellow with greenish tint, transparent with vitreous luster, non-fluorescent under ultraviolet light, and showing neither parting nor cleavage; Mohs hardness is 6.5. The density calculated on the basis of the empirical formula is 3.826 g/cm3. Its Raman spectrum shows strong bands at 522, 550 and 636 cm−1 and weak bands at 199, 260, 295, 456, and 754 cm−1.

Tululite, Ca 14 (Fe 3+ ,Al)(Al,Zn,Fe 3+ ,Si,P,Mn,Mg) 15 O 36 : a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

Flamite (Ca,Na,K)2(Si,P)O4 (P63; a = 43.3726(18), c = 6.8270(4) A; V = 11122.2(9) A3), a natural analogue of the P,Na,K-doped high-temperature α-Ca2SiO4 modification, is a new mineral from Ca- and Al-rich paralava, an ultrahigh-temperature combustion metamorphic melt rock. The type locality is situated in the southern Hatrurim Basin, the Negev Desert, Israel. Flamite occurs as regular lamellar intergrowths with partially hydrated larnite, together with rock-forming gehlenite, rankinite and Ti-rich andradite, minor ferrian perovskite, magnesioferrite, hematite, and retrograde ettringite and calcium silicate hydrates. The mineral is greyish to yellowish, transparent with a vitreous lustre, non-fluorescent under ultraviolet light and shows no parting or cleavage; Mohs hardness is 5–5½; calculated density is 3.264 g cm–3. The empirical formula of holotype flamite (mean of 21 analyses) is (Ca1.82Na0.09K0.06(Mg,Fe,Sr,Ba)0.02)Σ1.99(Si0.82P0.18)Σ1.00O4. The strongest lines in the powder X-ray diffraction pattern are [d, A (I obs )]: 2.713(100), 2.765(44), 2.759(42), 1.762(32), 2.518(29), 2.402(23), 2.897(19), 1.967(18), 2.220(15), 1.813(15). The strongest bands in the Raman spectrum are 170, 260, 520, 538, 850, 863, 885, 952 and 1003 cm–1.

S. V. Goryainov

Papers

Fossilized high pressure from the Earth's deep interior: The coesite-in-diamond barometer

Raman Spectroscopy of Water Tracer Diffusion in Zeolite Single Crystals

Raman identification of lonsdaleite in Popigai impactites

Tululite, Ca 14 (Fe 3+ ,Al)(Al,Zn,Fe 3+ ,Si,P,Mn,Mg) 15 O 36 : a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

Flamite, (Ca,Na,K)2(Si,P)O4, a new mineral from ultrahigh-temperature combustion metamorphic rocks, Hatrurim Basin, Negev Desert, Israel