Au(Ag)–Sn–Sb–Pb minerals in association with placer gold from Rumoi province of Hokkaido, Japan: a description of two new minerals (rumoiite and shosanbetsuite)

Nishio–Hamane, Daisuke; SAITO, Katsuyuki

doi:10.2465/jmps.210829

Cited by 2 publications

(1 citation statement)

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“…PGM are known to be derived from mafic and ultramafic rocks (e.g., O'Driscoll and González-Jiménez, 2016), and placer PGM deposits have been formed in Hokkaido and Kumamoto Prefecture, Japan (e.g., Suzuki, 1950;Nishio-Hamane et al, 2019). In Hokkaido, only the deposits surrounding current ultramafic rocks distributed along the Kamuikotan belt have been studied to date (Matsumoto, 1928;Aoyama, 1936;Mertie, 1969;Urashima et al, 1972Urashima et al, , 1974Urashima et al, , 1976Urashima and Nedachi, 1978;Urashima et al, 1982;Ohta and Nakagawa, 1990;Nakagawa et al, 1991;Matsubara, 1992;Nakagawa and Ohta, 1993), while PGM are also available from placer deposits in northwestern Hokkaido, Japan (e.g., Suzuki, 1950;Tsushima et al, 1954;Hata, 1961;Nishio-Hamane and Saito, 2021). However, no modern research has been done on northwestern Hokkai-do, where even the species of PGM, for example, are completely unknown to date.…”

Section: Introductionmentioning

confidence: 99%

Platinum–group minerals in the placer deposit in northwestern Hokkaido, Japan: description of a new mineral, tomamaeite

Nishio–Hamane

SAITO²

2022

Journal of Mineralogical and Petrological Sciences

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Mineralogical investigation of platinum-group minerals (PGM) from the placer deposit in northwestern Hokkaido, Japan, was conducted at six rivers and two coasts covering an area of 70 km north-south and 30 km east-west: the Moshosanbetsu River (M), the Shosanbetsu River (S), the Ainusawa River (A), the Tomamae coast (T), the Obira coast (OC), the Kamikinenbetsusawa River (K), the Obirashibe River (OR), and the Numatapon River (N) from north to south. Details of the major PGM grain and the occurrence of small but diverse PGM inclusions were revealed in this study. Among diverse PGM inclusions, Cu 3 Pt mineral was discovered in PGM placer from the coast of Tomamae town, and it has been approved as a new mineral, tomamaeite, named after the type locality, by the International Mineralogical Association, the Commission on New Minerals, Nomenclature and Classification (IMA-CNMNC). Later, tomamaeite was also discovered in five localities. Tomamaeite occurs in Pt-Fe(Cu) alloys such as tulameenite, ferronickelplatinum, tetraferroplatinum, and hongshiite as an anhedral particle with a size of less than 20 µm. Tomamaeite is an opaque mineral and has metallic luster with a pale mist white color in reflected light. The hardness of tomamaeite has yet to be determined, although it is estimated to be ~3½ from comparison with compositionally related minerals and the calculated density is 12.4 g•cm −3 using the empirical formula and powder X-ray diffraction data. The empirical formula of tomamaeite calculated on the basis of 4 apfu is (Cu 3.01 Fe 0.06 Ni 0.01 ) Σ3.08 (Pt 0.90 Ru 0.01 Rh <0.01 Pd <0.01 Os <0.01 Ir <0.01 ) Σ0.93 , (Cu 2.92 Fe 0.05 Ni 0.04 ) Σ3.01 (Pt 0.97 Pd 0.01 Rh 0.01 ) Σ0.99 , (Cu 2.86 Sb 0.13 Fe 0.03 Ni 0.02 ) Σ3.03 (Pt 0.92 Ir 0.02 Pd 0.01 Os 0.01 ) Σ0.97 , (Cu 2.71 Sb 0.19 Fe 0.02 Ni 0.02 ) Σ2.94 (Pt 1.01 Ir 0.05 ) Σ1.06 , (Cu 2.93 Fe 0.02 ) Σ2.94 (Pt 1.04 Rh 0.01 ) Σ1.06 , and (Cu 2.82 Fe 0.04 Ni 0.04 ) Σ2.90 (Pt 1.07 Ir 0.03 Pd <0.01 ) Σ1.10from the Tomamae coast, the Moshosanbetsu River, the Shosanbetsu River, the Ainusawa River, the Kamikinenbetsusawa River, and the Numatapon River, respectively. Crystal chemistry was investigated using tomamaeite from the Tomamae coast. Tomamaeite is cubic, Pm 3m, with lattice parameters a = 3.683(2) Å and V = 49.97(7) Å 3 (Z = 1) of Cu 3 Au-type structure, in which Pt occupies the position of origin, and Cu occupies the face-centered positions on a face-centered cubic lattice. PGM from northwestern Hokkaido probably have a mostly common origin and are characterized by depleted ultramafic rocks, and tomamaeite is a non-unique mineral that is formed during the universal postmagmatic process with alteration of such ultramafic rocks to serpentine.

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Section: Introductionmentioning

confidence: 99%

Platinum–group minerals in the placer deposit in northwestern Hokkaido, Japan: description of a new mineral, tomamaeite

Nishio–Hamane

SAITO²

2022

Journal of Mineralogical and Petrological Sciences

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Tomamaeite Cu3Pt in native osmium from river sediments in the Nizhnie Sergi Region, Central Urals

Sharygin

Mikhailov²

2022

Минералогия (Mineralogy)

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The article is devoted to tomamaeite Cu3Pt from inclusions in a native osmium grain from alluvial river sediments in the Nizhnie Sergi region, Sverdlovsk oblast. It is the fourth fnding of this mineral in the Urals. In addition to tomamaeite, native osmium Os0.36Ir0.33Ru0.31 contains the inclusions of digenite (or, possible, roxbyite), millerite, Fe-Ni-Pt alloy, an unidentifed Pd mineral, magnesiohornblendite, and low-Ca pyroxene. In composition, tomamaeite is close to ideal formula Cu3Pt and contains minor amounts of (wt. %) Pd (up to 2.0), Ir (up to 1.7), Ru and Ni (up to 0.6), and Fe (up to 0.2). In addition to native osmium, two grains of native ruthenium Ru0.54Os0.23Ir0.23 and Ru0.40Os0.31Ir0.29 are found in sediments. Our data suggest that PGE minerals in river sediments could be sourced from mafc-ultramafc massifs located in the Nizhnie Sergi area. The formation of tomamaeite and coexisted minerals is related to the process of postmagmatic transformation of the primary PGE mineral assemblage, probably, during serpentinization of ultramafc rocks.

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Au(Ag)–Sn–Sb–Pb minerals in association with placer gold from Rumoi province of Hokkaido, Japan: a description of two new minerals (rumoiite and shosanbetsuite)

Cited by 2 publications

References 16 publications

Platinum–group minerals in the placer deposit in northwestern Hokkaido, Japan: description of a new mineral, tomamaeite

Platinum–group minerals in the placer deposit in northwestern Hokkaido, Japan: description of a new mineral, tomamaeite

Tomamaeite Cu3Pt in native osmium from river sediments in the Nizhnie Sergi Region, Central Urals

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