mineral

Smoky Quartz with Siderite

Silicon Dioxide (SiO2) with Iron(II) Carbonate (FeCO3)

Hardness: 7 (Quartz) and 3.5-4.5 (Siderite); Color: brownish-grey smoky crystals with yellowish-brown siderite; Luster: Vitreous to pearly; Crystal structure: Trigonal/Hexagonal; Cleavage: None (Quartz) to Perfect rhombohedral (Siderite).

Hardness: 7 (Quartz) and 3
Color: brownish-grey smoky crystals with yellowish-brown siderite
Luster: Vitreous to pearly

Identified July 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins and granitic pegmatites. The smoky color in quartz is usually the result of natural irradiation from surrounding rocks over millions of years, while the siderite precipitates from iron-rich fluids.

Uses & applications

Used primarily as collector specimens and metaphysical stones. High-quality smoky quartz is used in jewelry and ornaments.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as Cairngorm. The dark color is caused by trace amounts of aluminum and exposure to radiation from radioactive elements like potassium or uranium in the host rock.

Field identification & locations

Identify by its smoky translucence and the presence of brownish rhombic siderite crystals. Commonly found in Brazil, Switzerland, and the United States (Colorado). Field collectors look for quartz veins in granite outcrops.

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sedimentary

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

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Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

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Mineral/Rock