Quartz

Quartz is the most abundant mineral exposed at Earth's surface — and despite its commonness, it produces some of the finest collector specimens in mineralogy. From Himalayan ice-clear crystals to the deep purple amethysts of Vera Cruz, quartz is the species every collector returns to.

Key Facts

• Mohs hardness 7 — the field reference for "hard" minerals.
• Piezoelectric: a crystal compressed along its axis generates a voltage. Used in oscillators and watches.
• No cleavage; breaks with a conchoidal fracture, like glass.
• Color forms vary so widely that varieties are sold under separate names in commercial markets.
• Hydrothermal pegmatites in Tibet and the Sichuan-Hubei border produce some of Asia's sharpest specimens.

Notable Varieties

• Amethyst (purple, Fe-bearing)
• Citrine (yellow, heat- or radiation-induced)
• Smoky Quartz (brown to black, radiation damage)
• Rose Quartz (pink, Ti/Fe inclusions)
• Rock Crystal (colorless)
• Morion (opaque black)

The Chinese Angle

Tibetan and Sichuan high-altitude pegmatites produce extraordinarily clear quartz crystals with fine terminations and minimal inclusions. The Yaogangxian district yields milky quartz matrix material for fluorite specimens, while Hunan produces some of the world's best fenster (window) quartz.