Rock Identifier
Druzy quartz geode slice (Quartz, SiO₂, commonly lining a chalcedony-rich geode) — mineral
mineral

Druzy quartz geode slice

Quartz, SiO₂, commonly lining a chalcedony-rich geode

AI-generated identification · may be incorrect

Typically white to gray or pale blue, with glassy to pearly luster and sparkling drusy microcrystals; quartz hardness is 7 Mohs, lacks cleavage, and has a hexagonal crystal structure. The cavities and banded chalcedony indicate a silica-filled vesicle or geode.

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Physical properties

Typically white to gray or pale blue, with glassy to pearly luster and sparkling drusy microcrystals; quartz hardness is 7 Mohs, lacks cleavage, and has a hexagonal crystal structure. The cavities and banded chalcedony indicate a silica-filled vesicle or geode.

Formation & geological history

Silica-rich groundwater deposited chalcedony and quartz in cavities of volcanic rock, commonly basalt, over long periods; the exact geological age cannot be determined from the image. It is often cut and polished into a display slice.

Uses & applications

Used as a decorative specimen, lapidary ornament, bookend, or jewelry component; quality depends on crystal sparkle, color, completeness, and size. Common commercial pieces sell for about $15–$75, with unusually attractive specimens reaching $100–$300.

Geological facts

The blue-gray color may reflect chalcedony, mineral inclusions, or mild enhancement; vivid uniform blue should be treated as potentially dyed. “Druzy” describes a coating of tiny crystals rather than a separate mineral.

Field identification & locations

Commonly found in volcanic regions such as Brazil, Uruguay, Mexico, Morocco, and the western United States. Identify it by sparkly quartz lining open cavities, waxy chalcedony bands, conchoidal fracture, and inability to scratch quartz with a steel knife.