Rock & Mineral Encyclopedia

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

Geode

A hollow rock nodule whose interior cavity is lined with inward-pointing crystals such as quartz, amethyst, or calcite.

A warm golden-brown garnet named for its honey color, typically a hessonite grossular variety with a distinctive treacly internal texture.

An orbicular jasper with red and orange flower-like spots resembling poppies, famously from Morgan Hill, California.

A naturally magnetized variety of magnetite that attracts iron, historically used as the first magnetic compass.

A common potassium feldspar identical in composition to orthoclase but more ordered, famous for its green gem variety amazonite.

The cinnamon-to-honey colored variety of grossular garnet, prized in jewelry and revered as the gem 'gomed' in Vedic astrology.

A soft, fine-grained, translucent form of gypsum (or banded calcite) long prized as a carving and ornamental stone.

A lightweight black organic gemstone formed from fossilized wood under pressure, a type of lignite long used in mourning jewelry.

A gray-brown jasper whose mottled, wrinkled patterning resembles elephant hide, also sold as Miriam or calligraphy stone.

A rosette-shaped cluster of bladed gypsum or barite crystals that traps sand, forming flower-like formations in arid deserts.

A dark green jasper-chalcedony speckled with red iron-oxide spots, classically known as bloodstone or heliotrope.

A fiery jasper whose red, orange, and yellow plumes lick across the stone like flames against an earthy background.

The blue-green gem variety of microcline feldspar, often mottled with white, prized as an affordable ornamental stone.

The soft pink, usually cloudy variety of quartz colored by trace titanium or microscopic inclusions, popular for carvings and beads.

A clear, soft crystalline variety of gypsum that forms glassy or fibrous wands, so soft it can be scratched with a fingernail.