mineral

Milky Quartz with Country Rock contact

Silicon Dioxide (SiO2) in contact with Metamorphic/Igneous rock

AI-generated identification · may be incorrect

Hardness: 7.0 (Mohs scale). Color: White/Opaque and Dark Grey/Black. Luster: Vitreous to greasy. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7
Color: White/Opaque and Dark Grey/Black
Luster: Vitreous to greasy

Identified April 15, 2026More mineral →

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Physical properties

Hardness: 7.0 (Mohs scale). Color: White/Opaque and Dark Grey/Black. Luster: Vitreous to greasy. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Formed through hydrothermal processes where silica-rich fluids filled veins or fractures in existing country rock. The dark portion represents the host rock wall. This type of formation occurs across most geological eras.

Uses & applications

Used primarily as decorative landscaping stone, in construction as aggregate, or as a source of high-purity silica for glass and electronics when found in large quantities.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Specimens like this that show a clear 'contact zone' between the vein and the wall rock are useful for geologists to study the heat and chemistry of mineral-forming fluids.

Field identification & locations

Identify by its ability to scratch glass and lack of cleavage. Often found in riverbeds or near mountain outcroppings. Collectors look for sharp contact lines or hidden crystal pockets inside the white mass.