Clear Quartz

Clear quartz, also called rock crystal, is the colorless, transparent form of crystalline quartz and one of the most abundant minerals in Earth's crust. When free of impurities it grows as glassy, water-clear hexagonal prisms.

Quartz is chemically simple—pure silicon dioxide—yet it is the parent species of an enormous family of colored varieties including amethyst, citrine, and rose quartz. Its hardness, chemical stability, and piezoelectric behavior (it generates a tiny voltage when squeezed) make it both a popular display crystal and a critical industrial material.

It has been carved into crystal balls, lenses, and beads for thousands of years.

Clear quartz crystallizes from silica-rich hydrothermal fluids that fill veins, cavities, and fractures in many rock types, as well as in pegmatites and igneous and metamorphic settings. Slow growth in open cavities produces the well-formed, transparent crystals prized by collectors.

Quartz is extremely common because silica is abundant and stable across a wide range of temperatures and pressures. Exceptional crystals come from Brazil, Arkansas (USA), Madagascar, and the Alps.

Quartz weathers out of rock to become the main component of most sand, making it abundant in sedimentary settings as well.

• Color: Colorless and transparent; cloudy white when included.
• Hardness: 7; readily scratches glass and is not scratched by a steel knife.
• Luster: Vitreous; conchoidal (shell-like) fracture and no true cleavage.
• Crystal form: Hexagonal prisms terminating in six-sided pyramids.

Look-alikes: Glass is softer (about 5.5) and won't scratch a real quartz crystal; glass often contains bubbles. Calcite is much softer (3) and fizzes in acid. Topaz is harder (8) and has good cleavage, unlike quartz's conchoidal fracture.

Clear quartz has major industrial uses: high-purity quartz is grown synthetically for oscillators in watches, radios, and computers thanks to its precise piezoelectric resonance. It is also used in optics, glassmaking, and abrasives.

As a lapidary and collector material, it is carved into spheres, points, beads, and figurines, and faceted as an inexpensive clear gem.

In metaphysical practice, clear quartz is regarded as an all-purpose "master" healing and amplifying crystal—claims that are cultural rather than scientific.