Quartz (Milky or Rough Quartz)

Hardness: 7 on the Mohs scale. Color: White to translucent/clear. Luster: Vitreous (glassy) to greasy. Crystal structure: Hexagonal/Trigonal. Cleavage: Poor/None (conchoidal fracture). Specific gravity: 2.65.

Formed through the cooling of silica-rich magma or from hydrothermal veins. It is found in all geological ages and forms in igneous, metamorphic, and sedimentary environments. This specific specimen appears to be a massive variety formed in a vein.

Extensively used in glass making, electronics (due to piezoelectric properties), abrasives, construction as a component of concrete, and as a semi-precious gemstone in jewelry or for decorative collecting.

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to both chemical and physical weathering, which is why it often remains as sand after other rocks have eroded away.

Identify in the field by its inability to be scratched by a steel knife (it will scratch glass instead) and its lack of cleavage planes. It is found globally, notably in pegmatites and mountain ranges. Collectors look for the absence of bubbles (differentiating it from glass) and its signature conchoidal fracture which looks like curved glass breaks.