mineral

Smoky Quartz with Siderite and Pyrite

Silicon Dioxide (SiO2) with Ferrous Carbonate (FeCO3) and Iron Sulfide (FeS2)

Hardness: 7 (Quartz) / 3.5-4 (Siderite). Color: Smoky brown, chocolate brown, metallic brassy-gold. Luster: Vitreous to sub-metallic. Crystal Structure: Hexagonal (Quartz) / Rhombohedral (Siderite).

Hardness: 7 (Quartz) / 3
Color: Smoky brown, chocolate brown, metallic brassy-gold
Luster: Vitreous to sub-metallic

Identified March 25, 2026More mineral →

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Physical properties

Hardness: 7 (Quartz) / 3.5-4 (Siderite). Color: Smoky brown, chocolate brown, metallic brassy-gold. Luster: Vitreous to sub-metallic. Crystal Structure: Hexagonal (Quartz) / Rhombohedral (Siderite).

Formation & geological history

Formed in hydrothermal veins or pegmatites where silica-rich fluids cooled over long periods. The smoky color in quartz is caused by natural irradiation of trace aluminum during its geological age, often spanning millions of years from the Paleozoic to Cenozoic eras.

Uses & applications

Primary use is for mineral specimen collecting and metaphysical displays. High-quality smoky quartz can be faceted for jewelry; siderite is occasionally used as a minor ore of iron.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm.' When associated with carbonates like siderite, it indicates a complex, multi-stage cooling environment in the earth's crust.

Field identification & locations

Identify in the field by the translucent brown color, lack of cleavage in the quartz sections, and the presence of brown, bladed, or rhombohedral siderite crystals. Commonly found in mountainous regions like the Alps, the Rockies, or the Ural Mountains.

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