mineral

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Opaque white with reddish-brown staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Opaque white with reddish-brown staining
Luster: Vitreous to greasy

Identified May 31, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Opaque white with reddish-brown staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in hydrothermal veins or pegmatites where silica-rich fluids cool and crystallize. The milky appearance is caused by tiny inclusions of gas or liquid, while the reddish streaks are from iron oxide (limonite or hematite) staining in cracks.

Uses & applications

Used primarily in lapidary work for cabochons and tumbled stones, landscaping, and as a collector's specimen. High-purity quartz is also used in the semiconductor industry.

Geological facts

Milky quartz is the most common variety of crystalline quartz. Historically, it was used by ancient civilizations for tools and decorative items due to its extreme hardness and durability.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife), white opaque color, and lack of cleavage. It is ubiquitous in mountainous regions and riverbeds globally.

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