mineral

Likely chert or chalcedony

Microcrystalline quartz (SiO₂), possibly waxy chalcedony or chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; tan to honey-brown, translucent at thin edges, with a waxy to dull luster and conchoidal-looking fracture. It appears massive rather than visibly crystalline; exact identification requires hardness and streak tests.

Identified September 20, 2026More mineral →

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Physical properties

Formation & geological history

Microcrystalline quartz forms when silica-rich groundwater precipitates in cavities, veins, or sediment pores; chert commonly forms through replacement or accumulation of siliceous material. The specimen’s geological age and locality cannot be determined from the image.

Uses & applications

Chert is used historically for tools and occasionally aggregate; attractive chalcedony is cut for cabochons, beads, and carvings. This small rough fragment has mainly educational or modest collecting value.

Geological facts

A steel knife should generally not scratch it, while quartz can scratch glass; its white streak and conchoidal fracture help distinguish it from calcite. Effervescence in dilute acid would suggest calcite instead, though none is apparent visually.

Field identification & locations

Common worldwide, especially in limestone terrains, sedimentary formations, and volcanic cavities. Estimated value: $1–$10 for an ordinary rough fragment, or up to $20–$50 if it proves to be attractive, translucent chalcedony.