Rock Identifier
Iridium sand or Osmium-Iridium nugget (Iridosmine / Osmiridium (Platinoid grouping)) — mineral
mineral

Iridium sand or Osmium-Iridium nugget

Iridosmine / Osmiridium (Platinoid grouping)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Steel-gray to tin-white; Luster: Metallic; Crystal Structure: Hexagonal; Specific Gravity: 18-21 (extremely heavy for its size).

Hardness
6-7 Mohs
Color
Steel-gray to tin-white
Luster
Metallic
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Physical properties

Hardness: 6-7 Mohs; Color: Steel-gray to tin-white; Luster: Metallic; Crystal Structure: Hexagonal; Specific Gravity: 18-21 (extremely heavy for its size).

Formation & geological history

Formed in ultramafic igneous rocks as primary minerals or more commonly found in secondary alluvial (placer) deposits alongside gold and platinum due to extreme weather resistance.

Uses & applications

Used in high-strength alloys, electrical contacts, fountain pen nib tips, and specialized bearings. Primarily a source for iridium and osmium, two of the rarest elements on Earth.

Geological facts

Iridium is considered one of the rarest elements in the Earth's crust; its concentration in certain geological layers (the K-Pg boundary) is used as evidence for the asteroid impact that killed the dinosaurs.

Field identification & locations

Identify by its incredible density/weight compared to size and its resistance to all common acids. It will not dissolve in aqua regia, unlike gold.

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