Gal'moenan ultrabasic massif, Korf, Olyutorsky district, Koryak Okrug, Kamchatka Krai, Russiai

Regional Level Types
Gal'moenan ultrabasic massif	Massif
Korf	Village (Former)
Olyutorsky district	District
Koryak Okrug	Division
Kamchatka Krai	Krai
Russia	Country

Ural–Alaskan type layered intrusion, mainly consisting of dunite, clinopyroxenite, and gabbro (wehrlite and serpentinite also occur). Dunites occupy ca. 70% of the area in the center, and clinopyroxenite, wehrlite, and gabbro occur near the periphery.

The numerous lode occurrences of PGMs (Platinum-Group Metals) are related to three types of ore deposits: Pt-bearing dunites, Pt-bearing chromitites, and PGMs hosted in titanomagnetite-bearing clinopyroxenites. Chromian spinel (chromite) forms layers, veinlets and schlieren up to 30 cm thick in dunite. Isoferroplatinum is the main PGM mineral in all the three types of ore deposits. The secondary Pt–Fe–Cu alloys rim the Pt–Fe grains and make up a complete series from tetraferroplatinum to tulameenite and a limited series toward the Cu₃Pt phase (tomamaeite) with sporadic Ni admixture up to 5 at %. Tetraferroplatinum is characteristic of dunite, while Cu-rich compounds (tulameenite) are characteristic of chromitite. Other PGM were identified as inclusions in platinum or as intergrowths with it. The Pt–Os and Pt–Ir assemblages are distinguished; the latter is prevalent. Laurite forms rare inclusions; sperrylite rims tulameenite or forms openwork individuals in serpentine, and small irarsite grains at the front of substitution of platinum for tulameenite occur in association with Fe–Pt alloys. Hexaferrum, Pt oxides, and porous magnetite occur sporadically at the contact between platinum and serpentine (Kozlov et al., 2011). The phase (Pt_0.96Fe_0.02)(As_1.17Sb_0.75S_0.09), a member of the sperrylite – geversite solid solution, has been found in a lode (Tolstykh et al., 2004).

Streams draining the intrusion (Levtyrinyvayam River in the east, Gal'motapel'vayam river in the north; Vetvisty and Penisty creeks in the west, Ledyanoy Creek to the southwest, and Yuzhny Creek in the south) have formed PGM placers around it.

Ascribable to the ultrabasic massif are the three currently worked PGM placers along the River Levtyrinyvayam and the creeks Ledyanoy and Penisty, and numerous lode deposits.


Minor elements, which are indicators of conditions of formation of the Pt–Fe alloy, exhibit different concentrations in lodes and in the nearby placers. Platinum–iron alloy from the Levtyrinyvayam placer, the farthest from the source, represents the eroded upper apical part of the intrusion, and contains mainly Pd. The Penisty placer receives platinum from dunite and pyroxenite of a marginal facies of the complex, and thus platinum–iron alloy contains Rh–Ir and Pd–Rh. Placer isoferroplatinum deposited along the Ledyanoy Creek, which drains dunite and chromite-bearing rocks in the south of the intrusion, is rich in Ir (up to 6.98 wt.%), as is the Pt–Fe alloy in the Gal’moenan complex (4.34 wt.% Ir). Most grains contain also a relatively high Rh content. Isoferroplatinum + iridium and isoferroplatinum + osmium are two main primary magmatic parageneses revealed in both placers and lodes, though the first is more commonly found in lodes and in the Ledyanoy Creek placer, and the latter in the Levtyrinyvayam River placer. Lodes mostly contain laurite and the Levtyrinyvayam placer bears all varieties of (Ru,Os)S₂, including Ru-free Rh-rich erlichmanite (Os,Rh)S₂. The irarsite – hollingworthite series predominates in lodes, and the irarsite – platarsite and osarsite – platarsite series predominate in the Levtyrinyvayam placer. Sperrylite in lodes may contain up to 6.94 wt.% Sb, and thus differs from that in placers.

The local pentlandite relics (found within awaruite) are unusually rich in Os, at max. 540 ppm.

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Wikidata ID:	9

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