Amethyst

Hardness: 7 on the Mohs scale; Color: Purple, ranging from pale lilac to deep violet; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal system), often forming as prismatic crystals with pyramidal terminations or drusy coatings; Cleavage: None, exhibits conchoidal fracture; Specific Gravity: 2.65

Amethyst forms in hydrothermal veins and vugs in igneous rocks, specifically in basaltic lavas. It crystallizes from silica-rich fluids at relatively low temperatures and pressures. The purple color is due to irradiation of trace amounts of iron within the quartz structure. Geological age varies widely depending on the deposit, but many prominent deposits date back millions to hundreds of millions of years.

Amethyst is widely used as a gemstone in jewelry due to its attractive purple color. It is fashioned into faceted stones, cabochons, beads, and carvings. Larger specimens are popular for mineral collecting and display. In metaphysical beliefs, amethyst is associated with calming and spiritual properties.

Amethyst is the birthstone for February. Large geodes lined with amethyst crystals are a prominent feature in many mineral collections, particularly those from Brazil and Uruguay. The color of amethyst can fade with prolonged exposure to sunlight or heat. Heating amethyst can turn it yellow (citrine) or green (prasiolite).

In the field, amethyst is identified by its distinctive purple color and characteristic hexagonal crystal habit. It is often found in geodes, vugs, or veins within volcanic or granitic rocks. Common locations include Brazil (Rio Grande do Sul), Uruguay, Siberia (Russia), Zambia, Canada, and various localities in the United States. Tips for collectors include looking for geode formations or veins in silica-rich environments. The depth and evenness of the purple color are key indicators of quality.