Jasper

Hardness: 7 (Mohs scale), Color: Brown, reddish-brown, yellow-brown, Luster: Vitreous to greasy, Crystal Structure: Trigonal, Cleavage: None, Specific Gravity: 2.65

Jasper forms from the precipitation of silica from water in various environments, including volcanic rocks, hydrothermal vents, and sedimentary deposits. The red and brown colors are due to impurities of iron oxides (hematite and goethite). Its geological age can vary widely, from Precambrian to Cenozoic.

Jasper is primarily used as an ornamental stone in jewelry (cabochons, beads), carvings, and decorative objects. Larger pieces are used for architectural cladding, sculptures, and inlays. Historically, it was used for tools and seals.

Jasper is a cryptocrystalline variety of quartz, meaning its crystals are too fine to be seen without a microscope. It often forms beautiful patterns and is found in various shades of red, yellow, brown, and green due to iron oxide impurities. The name 'jasper' means 'spotted or specked stone' and is derived from Greek and old French.

In the field, jasper can be identified by its characteristic earthy colors (brown, red, yellow), its dull to waxy luster, and its hardness (it can scratch glass). It typically forms in nodules or fills fissures in other rocks. Commonly found worldwide in areas with volcanic activity or sedimentary rock formations, including the Western United States, Egypt, India, and Australia. Look for its distinctive opaque appearance and often banded or mottled patterns. Collectors appreciate its wide range of colors and patterns.