mineral
Yellow chalcedony or quartz fragment
Microcrystalline quartz, SiO₂ (tentative; possibly iron-stained chalcedony)
AI-generated identification · may be incorrectSmall yellow-tan, translucent to opaque, waxy-to-dull specimen with an apparently irregular fracture and no obvious cleavage. Quartz has Mohs hardness 7, vitreous luster when fresh, and specific gravity about 2.65; the image is insufficient for confident determination.
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Physical properties
Small yellow-tan, translucent to opaque, waxy-to-dull specimen with an apparently irregular fracture and no obvious cleavage. Quartz has Mohs hardness 7, vitreous luster when fresh, and specific gravity about 2.65; the image is insufficient for confident determination.
Formation & geological history
Likely silica deposited from groundwater in cavities or veins, with yellow coloration from iron-oxide staining or inclusions; formation age cannot be determined visually. It may also be a weathered fragment of a larger quartz-rich rock.
Uses & applications
Common chalcedony is used for lapidary work, cabochons, carvings, and decorative stone; small unattractive fragments have little practical value.
Geological facts
Quartz is one of Earth’s most abundant minerals and forms in igneous, sedimentary, and metamorphic environments. Chalcedony is a cryptocrystalline variety composed mainly of intergrown quartz fibers.
Field identification & locations
Test with a steel file or glass: true quartz should scratch glass and resist a steel blade. Common sources include volcanic cavities and silica-rich veins worldwide; a close photo, locality, translucency, and hardness test are needed for identification.
