Formula: Pd11Sb2As2
Arsenide, isomertieite group, paramorph of mertieite, palladium-bearing mineral
Fengluanite is an antimony-rich variety of isomertieite
Specific gravity: 10,33 calculated
Hardness: 5½
Colour: Pale yellow in reflected light
Common impurities: Au,Cu

Metamorphic environments
Hydrothermal environments

Isomertieite occurs in heavy metal concentrates with gold and other palladium minerals (Dana).


At the type locality, Itabira, Minas Gerais, Brazil, isomertieite occurs In heavy-metal concentrates from Precambrian iron-precious metal deposits. Associated minerals include arsenopalladinite, atheneite, palladseite, hematite and gold (MM 39.528-543, HOM, Mindat).

At the Lac des Iles Complex, Lac des Iles Area, Thunder Bay District, Ontario, Canada, isomertieite is associated with chalcopyrite, millerite, kotulskite, arsenopalladinite and hematite (HOM). The complex is a mafic-ultramafic intrusive complex with gabbro and pegmatites, that contains several platinum group element (PGE) mineralisations (Mindat).

At the Hongshila Pt-Pd deposit, Boluonuo, Fengning County, Chengde, Hebei, China, isomertieite is associated with hongshiite, cooperite, sperrylite, vysotskite, magnetite, bornite, polydymite, diopside, actinolite and epidote (HOM). The deposit is a platinum group element (PGE)-bearing ultramafic body, intruded into metamorphic rocks, mainly hornblende-plagioclase gneiss, with minor schist and marble (Mindat).

At Hope's Nose, Torquay, Torbay, Devon, England, UK, gold alloyed with up to 16% palladium occasionally hosts tiny crystals of isomertieite and mertieite (R&M 96.3.202). The deposit is in precious (Au, Ag, Pd) and base metal selenide mineralisation in calcite veins (Mindat).

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