Magmatic to hydrothermal metal fluxes in convergent and collided margins

Phanerozoic continental growth and gold metallogeny of Asia

This report deals with a general reexamination of the systematics of sulfosalts. It represents an update of the activity of the Sulfosalt Sub-Committee within the Commission on Ore Mineralogy of the International Mineralogical Association, in connection with the Commission on New Minerals, Nomenclature and Classification (CNMNC-IMA). Part I presents generali- ties of sulfosalt definition and nomenclature. After an extended chemical definition of sulfosalts, attention is focused on "classic" sulfosalts with As 3+ ,S b 3+ ,B i 3+ or Te 4+ as cations, corresponding to the general formula (Me + , Me' 2+ , etc.)x ((Bi, Sb, As) 3+ , Te 4+ )y ((S, Se, Te) 2− )z (Me, Me': various metals). General aspects of their chemistry and classification principles are summarized, especially with regard to chemical substitutions and modular analysis of complex crystal structures. On this basis, Part II presents a review of sulfosalt systematics. Six main crystal-chemical sub-groups are distinguished (plus some unclassified species), con- cerning more than 220 valid mineral species. Among others whose status is questioned are those considered to be varieties of well-defined species; minerals with ill-defined X-ray data; those that are possibly identical species; and those that represent the potential revalidation of old species. More than 50 crystal structures still remain unsolved, among which about a half probably corresponds to new structure types.

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Sulfosalt systematics: a review. Report of the sulfosalt sub-committee of the IMA Commission on Ore Mineralogy

Infrared Spectroscopy of Minerals and Related Compounds

The chapter presents an overview of the chemistry of transport and deposition of metals by aqueous fluids under hydrothermal conditions that are responsible for the formation of ore deposits throughout the Earth's crust. Metal complex equilibria at elevated temperatures and pressures are considered in relation to modern knowledge of water solvent structure and properties as well as electrolyte solution behavior under extreme conditions. The recent advances in our knowledge of the stoichiometry and stability of metal complexes from experimental and ab initio studies are discussed within the context of hydrothermal fluids having liquid-like densities and those having gas-like densities.

The Chemistry of Metal Transport and Deposition by Ore-Forming Hydrothermal Fluids

The Maiskoe multimegastage disseminated gold-sulfide deposit (Chukotka, Russia): Mineralogy, fluid inclusions, stable isotopes (O and S), history, and conditions of formation

Minerals of the system ZnS–CdS formed between 400 and 725°C in active fumaroles at the Kudriavy volcano, Iturup Island, Russia, were studied using scanning electron microscopy with energy dispersion, X-ray diffraction and with an electron microprobe. The composition of these minerals varies widely: Zn 2.46–57.7, Cd 2.38–69.5, Fe 0.72–13.6 wt.%, and thus covers almost the entire ZnS–CdS series. Two types of solid solutions occur: cubic, from 0 to ∼8 mol.% CdS, and hexagonal, from α17 to 100 mol.% CdS, separated by a two-phase transition zone. Three different mechanisms of substitution account for the range of composition: Zn-for-Fe in sphalerite, Zn-for-Cd in wurtzite–greenockite, and Cd-for-Fe in greenockite. The incorporation of Cu and In, up to 2.92 and 4.75 wt.%, respectively, is noted in sphalerite, and up to 1.27 wt.% Cu and 2.75 wt.% In, respectively, in minerals of the wurtzite–greenockite series. Both elements evidently occur as the roquesite component in solid solution. Zinc-rich species are metal-deficient, whereas Cd-rich species are sulfur-deficient. The range of nonstoichiometry in minerals of the system ZnS–CdS studied is in the order of 2.6 at.%, or 0.05 apfu S. We conclude that there is not a complete solid-solution between wurtzite and greenockite in the temperature range studied owing to a phase transition in ZnS and a change in the structure type. Phase relations for the temperature range studied proved to be identical with those established for synthetic compounds. In a fumarolic environment, crystals of Cd-rich sulfides of the system ZnS–CdS precipitate mainly at lower temperatures (400°C) than those of Zn (up to 725°C).

MINERALS OF THE SYSTEM ZnS–CdS FROM FUMAROLES OF THE KUDRIAVY VOLCANO, ITURUP ISLAND, KURILES, RUSSIA

Kudriavite, a new mineral species, occurs as a high-temperature (about 400°C) fumarole incrustation in the steep inner wall of the crater rim of Kudriavy volcano, on Iturup Island, in the Kurile arc, Russia. Associated minerals are cannizzarite, greenockite and pyrite. The mineral occurs as elongate slender platy opaque crystals up to 0.4 × 0.2 × 0.02 mm, usually striated along the elongation. Box-shaped skeletal crystals also are common. The color is dark grey, with a slightly reddish hue and a metallic luster. The streak is black. Crystals of kudriavite have an uneven fracture and are very brittle. Reflectance values for the COM wavelengths [% (R1, R2)] are: 470 nm (36.4, 29.6), 546 nm (38.8, 32.4), 589 nm (38.2, 31.8), and 650 nm (37.7, 31.4). The bireflectance is distinct; the anisotropy is rather strong, but without color effect. Its measured microhardness VHN10 is 129. The electron-microprobe analysis of holotype kudriavite gave Cd 8.25, Pb 13.10, Fe 0.17, Mn 0.26, Bi 55.37, In 2.80, Tl 0.02, S 17.70, Se 2.23, Cl 0.02, sum 99.92 wt.%. The empirical formula, based on seven atoms, is (Cd0.51Pb0.44Fe0.02Mn0.03)∑1.00 (Bi1.83In0.17)∑2.00 (S3.81Se0.19)∑4.00; the idealized formula is (Cd,Pb)Bi2S4. The ideal formula CdBi2S4 requires Cd 17.07, Bi 63.46, S 19.47, for a total of 100.00 wt.%. The strongest nine lines of the X-ray powder-diffraction pattern [ d in A( I )( hkl )] are: 3.715(m)(202), 3.632(m)(204),3.520(s)(112), 3.274(s)(004, 402), 3.169(m)(112), 2.948(s)(311), 2.809(s)(310), 2.346(m)(114, 115), and 1.914(m)(511). The unit-cell parameters of kudriavite, determined on a single crystal, are: a 13.095(1), b 4.0032(3), c 14.711(1) A, β 115.59(1)°, V 695.5(1) A3, Z = 4, space group C 2/ m , Dcalc = 6.578 g/cm3. According to the solution of the structure, kudriavite is the first natural homologue N = 3 of pavonite. The mineral (IMA No. 2003–011) is named after the discovery locality.

KUDRIAVITE, (Cd,Pb)Bi2S4, A NEW MINERAL SPECIES FROM KUDRIAVY VOLCANO, ITURUP ISLAND, KURILE ARC, RUSSIA

Enthalpy of formation of natural hydrous iron phosphate: Vivianite

Three generations of tourmaline have been identified in propylite in the Vetka porphyry copper-molybdenum deposit of the Chukchi Peninsula of Russia. Tourmaline-I is characterized by its Fetot/(Fetot + Mg) value, which ranges from 0.33 to 0.49. Tourmaline-II, which crystallizes at a lower temperature, overgrowing tourmaline-I or occurring as isolated crystals, is distinguished by a higher Fetot/(Fetot + Mg), which varies from 0.46 to 0.72. The Fetot/(Fetot + Mg) ratio in tourmaline-III, which overgrows tourmaline-II is lower (0.35–0.49), and is identical to that of the first tourmaline generation. This is probably caused by the beginning of sulfide deposition. Tourmalines in the deposit characterized by complex isomorphic substitutions can be attributed to the intermediate members of the dravite—“hydroxy-uvite”-“oxy-uvite” and schorl-“hydroxy-feruvite”-“oxy-feruvite” series. Tourmaline starts to crystallize at temperatures above 340°C. The fluid responsible for the tourmaline deposition was magmatic, with a significant admixture of meteoric water (δ18OH2O = −0.85 to −0.75‰). The high Fe3+/Fetot ratio (0.50) indicates high oxygen activity when the tourmaline precipitated. It has been established that the isomorphic substitution Fetot → Al is typomorphic of tourmalines from porphyry copper deposits worldwide.

I. A. Bryzgalov

Papers

The Maiskoe multimegastage disseminated gold-sulfide deposit (Chukotka, Russia): Mineralogy, fluid inclusions, stable isotopes (O and S), history, and conditions of formation

MINERALS OF THE SYSTEM ZnS–CdS FROM FUMAROLES OF THE KUDRIAVY VOLCANO, ITURUP ISLAND, KURILES, RUSSIA

KUDRIAVITE, (Cd,Pb)Bi2S4, A NEW MINERAL SPECIES FROM KUDRIAVY VOLCANO, ITURUP ISLAND, KURILE ARC, RUSSIA

Enthalpy of formation of natural hydrous iron phosphate: Vivianite

Tourmaline in the Vetka Porphyry Copper-Molybdenum Deposit of the Chukchi Peninsula of Russia