mineral

Quartz druzy/geode specimen

Microcrystalline quartz, silicon dioxide (SiO₂), likely coating a carbonate-rich host

AI-generated identification · may be incorrect

White to pale gray, sparkling drusy crystals with vitreous luster; quartz is Mohs hardness 7, trigonal crystal system, and lacks cleavage. The rough outer material appears porous and may include calcite or weathered carbonate matrix, which is softer (Mohs 3).

Identified September 6, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-bearing fluids deposit tiny quartz crystals on cavity walls or porous carbonate rock, commonly during late-stage hydrothermal or groundwater activity. The exact geological age cannot be determined from the photograph.

Uses & applications

Primarily a display and collector specimen; attractive pieces are used in mineral décor and occasionally lapidary work. It has little industrial value in this form.

Geological facts

The glittering surface is called druzy or druse, produced by thousands of microscopic crystal tips rather than one large crystal. Acid testing of any exposed carbonate matrix can help distinguish calcite from quartz.

Field identification & locations

Commonly found in geodes, limestone cavities, volcanic vesicles, and hydrothermal veins; notable sources include Brazil, Uruguay, Morocco, and the United States. Avoid harsh cleaning acids if calcite is present, since they can dissolve the matrix.