mineral
Botryoidal chalcedony (white agate)
Microcrystalline quartz, SiO₂ (chalcedony)
AI-generated identification · may be incorrectPale gray-white, waxy to dull luster, with rounded, knobby growths and subtle banding; hardness about 6.5–7 Mohs. Quartz is trigonal at the crystal level, though chalcedony’s crystals are microscopic; cleavage is absent and fracture is conchoidal.
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Physical properties
Pale gray-white, waxy to dull luster, with rounded, knobby growths and subtle banding; hardness about 6.5–7 Mohs. Quartz is trigonal at the crystal level, though chalcedony’s crystals are microscopic; cleavage is absent and fracture is conchoidal.
Formation & geological history
Silica-rich fluids deposited layers in cavities and fractures, likely forming the rounded surface by successive growth. Chalcedony occurs in rocks of many ages; the image alone cannot determine this specimen’s age.
Uses & applications
Polished pieces are used for ornaments, lapidary work, and sometimes jewelry; similar material is also collected as a mineral specimen.
Geological facts
Chalcedony is a compact aggregate of tiny quartz crystals and may display concentric bands when cut. The specimen’s pale color and knobby texture suggest botryoidal growth.
Field identification & locations
Look for a dense, smooth-waxy surface, hardness near 7, and conchoidal fracture; it is commonly found in volcanic cavities and veins worldwide. Exact identification is uncertain from the image alone.
