The Mineral sperrylite

Sperrylite is a rare mineral composed primarily of the precious metal platinum. Aside from native Platinum, Sperrylite is the only platinum ore of any economic importance. It forms in highly lustrous crystals that can be very well-formed, making this mineral a novelty for collectors due to its value. Sperrylite is named after Francis Louis Sperry (1861-1906), a chemist who discovered this mineral at Sudbury, Ontario in 1889.

Chemical Formula

PtAs₂

Composition

Platinum arsenide

Color

Tin white

Streak

Dark gray to black

Hardness

6 - 7

Crystal System

Isometric

3D Crystal Atlas
(Click for animated model)

Crystal Forms
and Aggregates

In cubes with modified octahedral faces, and less commonly octahedral with modified cubic faces. Crystals, which are never large, may be in grouped clusters or individually formed. Also in distorted crystal groups and irregular fractured crystal masses. Crystals often contain irregular surface cracks.

Transparency

Opaque

Specific Gravity

10 - 11

Luster

Metallic

Cleavage

3,3

Fracture

Conchoidal

Tenacity

Brittle

In Group

Sulfides; Arsenides

Striking Features

Color, crystal habit, high hardness and specific gravity, and mode of occurrence

Environment

In plutonic mafic rocks such as greenstones and quartzite, and in alluvial deposits.

Rock Type

Igneous, Sedimentary, Metamorphic

Popularity (1-4)

Prevalence (1-3)

Demand (1-3)

Sperrylite AUCTIONS

USES

Sperrylite is an important ore of the precious metal platinum, and good crystals are highly valued by mineral collectors.

NOTEWORTHY LOCALITIES

The original locality where Sperrylite was first identified is the Vermilion Mine, Denison Township, Sudbury District, Ontario. This famous locality still produces small lustrous crystals in the old mine dumps. Another well-known Sperrylite deposit in the Sudbury District is the Broken Hammer Deposit, Wisner Township, which produces crystals in very sharp form.

The largest and best-formed Sperrylite crystals come from the Talnakh deposit, near Noril'sk, Eastern-Siberian Region, Russia. Sperrylite is of economic value and mined for its platinum content at the Bushveld Complex, Limpopo Province, South Africa. In the U.S., waterworn crystals were found in alluvial placer deposits at Mason Mountain, Macon County, North Carolina.

COMMON MINERAL ASSOCIATIONS