mineral

Quartz (likely Chalcedony or Chert)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Translucent tan to creamy white with yellowish iron staining. Luster: Waxy to vitreous. Crystal structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent tan to creamy white with yellowish iron staining
Luster: Waxy to vitreous

Identified June 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms from the precipitation of silica from groundwater or hydrothermal fluids in volcanic rocks, limestone, or as a secondary replacement in sedimentary environments. Can date from various geological eras depending on location.

Uses & applications

Commonly used as an abrasive, in glassmaking, and for making stone tools historically. In this form, it is primarily a landscape or gravel specimen or of interest to amateur collectors.

Geological facts

This specimen displays a typical conchoidal fracture (curved, glass-like breaks) which made this stone type ideal for ancient humans to create percussion-flaked tools like arrowheads and scrapers.

Field identification & locations

Identify in the field by its waxy appearance, its ability to scratch glass (Hardness 7), and the absence of reacting to acid. Commonly found in riverbeds, gravel pits, and desert washes.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic