Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Feldspar

The most abundant mineral group in Earth's crust, feldspars are aluminosilicates that form much of granite and many igneous rocks.

A striking platy, blade-like variety of albite feldspar that grows in fanned aggregates of thin white crystals within granite pegmatites.

A high-grade metamorphic gneiss of garnet, sillimanite, quartz, and graphite, derived from ancient aluminous sediments.

A richly colored red banded agate prized by lapidaries for its deep crimson-to-brown tones reminiscent of pigeon's blood.