Rock & Mineral Encyclopedia

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

Gem Silica

A rare, intensely blue chalcedony colored by copper-rich chrysocolla, prized as the most valuable of the blue chalcedonies.

A fossiliferous jasper packed with spiral snail shells, technically a silicified gastropod limestone from Wyoming.

An opaque jasper from the Cave Creek area of Arizona, prized for earthy mottled and banded patterns in warm desert tones.

A prized Oregon picture jasper from the Deschutes region known for soft scenic landscapes in cream, tan, and blue-gray.

Quartz containing a sealed pocket of ancient water, often with a mobile air bubble that moves when the crystal is tilted.

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

A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.

An opaque patterned jasper named for its scaly, snakeskin-like surface markings of interlocking tan and brown cells.

A black-and-white striped chalcedony-quartz rock whose bold zebra-like banding makes it a popular ornamental and lapidary stone.

Ancient wood whose organic tissue has been replaced by silica, preserving the grain, rings, and structure of the original tree in stone.

A translucent, soft blue variety of microcrystalline quartz whose color comes from light scattering through its fine structure.

A fossiliferous limestone built largely from the disc-shaped skeletal plates of crinoids, marine animals known as sea lilies.

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

A regional Russian name for a moonstone-like plagioclase from the White Sea coast, prized for its bluish, slightly iridescent schiller.

A rare sky-blue variety of pectolite found only in the Dominican Republic, prized for its sea-like color and white volcanic patterning.