Amethyst (variety of Quartz)

Hardness: 7 on Mohs scale; Color: Purple (from pale lilac to deep violet), often with zones of color; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Amethyst forms in volcanic rocks (geodes and vugs), hydrothermal veins, and occasionally in alluvial deposits. The purple color is due to irradiation of iron impurities within the quartz crystal lattice. Its formation typically occurs in the late stages of igneous activity, as silica-rich fluids cool and crystallize. Geological Age: Varies widely, but many significant deposits are found in rocks from the Proterozoic to Cenozoic eras.

Predominantly used in jewelry (rings, necklaces, earrings, bracelets like the one shown), ornamental carvings, and as collectible mineral specimens. Lower grades may be crushed for industrial abrasives or used in some electronic components due to its piezoelectric properties, though clearer quartz is preferred for this.

Amethyst is the most popular and commercially valuable variety of quartz. Its name comes from the Greek word 'amethystos,' meaning 'not drunken,' as it was believed to protect its wearer from intoxication. Heat treatment can change the color of amethyst to yellow, orange, or brown (citrine) or green (prasiolite).

To identify in the field, look for its distinctive purple color and characteristic hexagonal crystal habit, often found lining cavities in basalt or other volcanic rocks. It has a hardness of 7, meaning it can scratch glass and steel. Common locations include Brazil (producing the largest geodes), Uruguay, Siberia (Russia), Zambia, Bolivia, and parts of the United States (e.g., Arizona, North Carolina). Collectors look for deep, even purple color and good clarity.