Rock & Mineral Encyclopedia

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

Palagonite

A yellow-brown alteration material formed when basaltic volcanic glass reacts with water, common in hydrovolcanic tuffs and pillow lavas.

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

Fine, golden, hair-like strands of basaltic volcanic glass spun from fluid lava droplets during eruptions, named for the Hawaiian volcano goddess.

Small, smooth, teardrop-shaped beads of basaltic volcanic glass formed from airborne lava droplets, often paired with Pele's hair.

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.

Basalt that has been metamorphosed, developing new minerals like chlorite, actinolite, and epidote that give it a greenish color.

A chalcedony agate with soft, billowing cloud-like masses of gray and white suspended in a translucent body.

A gray-toned jasper with swirling cream, black, and brown leaf-like patterns, sometimes with druzy or agate pockets.

A soft lead-gray bismuth sulfide that is an important ore of bismuth, forming metallic needle-like and bladed crystals.

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.

A mottled, multicolored obsidian blending black, brown, grey, and tan patches like a calico cat's patchwork coat.

The blue-grey relative of tiger's eye, a chatoyant quartz showing a shifting band of light like a bird of prey's eye.

A black volcanic glass threaded with delicate grey, swirling lace-like bands of flow lines that show beautifully when polished.