Rock & Mineral Encyclopedia

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

Lake Michigan Agate

Glacially deposited banded agates found along Lake Michigan beaches, small waterworn pebbles with concentric red and grey banding.

Opal showing a smooth, silky satin-like sheen across its surface, valued for a gentle, refined luster.

A dull, resinous volcanic glass similar to obsidian but with higher water content and a waxy pitch-like luster.

A transparent, colorless opal that looks like water or jelly, sometimes flashing subtle play-of-color from within.

An earthy-toned jasper with vine-like or scenic patterning, valued by lapidaries for warm browns, reds, and creams that polish to a smooth finish.

A water-bearing massive grossular garnet, usually green or pink, widely used as a tough jade-like carving stone.

A translucent, gelatinous-looking opal whose transparency gives floating, glowing play-of-color a watery, jelly-like appearance.