Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Biggs Jasper
A classic Oregon picture jasper showing layered tan, brown, and blue-grey scenes resembling desert landscapes and canyons.
mineral
Peacock Opal
A precious opal showing dominant peacock-like blue, green and teal play-of-color, often on Ethiopian material.
gemstone
Sapphire
The gem variety of corundum in every color except red, most prized in velvety blue and exceptionally hard and durable.
gemstone
Hawk's Eye
The blue-grey relative of tiger's eye, a chatoyant quartz showing a shifting band of light like a bird of prey's eye.
gemstone
Anhydrite
A water-free calcium sulfate mineral closely related to gypsum, forming in evaporite deposits and swelling into gypsum when it absorbs water.
mineral
Aquamarine Crystal
The blue iron-bearing variety of beryl, forming clear hexagonal crystals prized both as specimens and as a March birthstone gem.
crystal
Chalcedony
A waxy, translucent microcrystalline form of quartz that serves as the parent group for agate, jasper, carnelian, and onyx.
mineral
Sodalite
A royal-blue feldspathoid mineral with white calcite veining, often confused with lapis lazuli but lacking its golden pyrite flecks.
mineral
Galena
A heavy, lead-grey metallic mineral with perfect cubic cleavage, galena is the world's main ore of lead and often carries silver.
mineral
Paraiba Tourmaline
An intensely glowing copper-bearing tourmaline famed for its electric neon blue-green color and extreme rarity and value.
gemstone
Color Change Garnet
A rare garnet that dramatically shifts color from greenish in daylight to reddish under lamplight, rivaling alexandrite.
gemstone
Amazonite
The blue-green gem variety of microcline feldspar, often mottled with white, prized as an affordable ornamental stone.
mineral
Zircon
A natural zirconium silicate gem with high brilliance and fire, often confused with the synthetic imitation cubic zirconia.
gemstoneGrey Moonstone
A smoky gray feldspar moonstone, often called new moon stone, showing a silvery-blue adularescent sheen over a translucent gray body.
gemstone
Celestite
A soft, sky-blue strontium sulfate mineral famous for the glittering pale-blue crystal geodes from Madagascar.
mineral
Black Opal
The rarest and most valuable opal, with a dark body tone that makes its flashing rainbow play-of-color blaze brilliantly.
gemstoneTurquoise Obsidian
A vivid turquoise-blue glass sold as obsidian; this bright color is virtually always manufactured rather than natural volcanic glass.
igneousRainbow Moonstone
A near-colorless feldspar showing blue and multicolored sheen; gemologically a white labradorite rather than true orthoclase moonstone.
gemstone
Moonstone
A feldspar gem famous for adularescence, a floating blue-white glow that shimmers across the stone like moonlight.
gemstone
Hemimorphite
A hydrous zinc silicate, often sky-blue, that is an ore of zinc and a collectible mineral forming botryoidal crusts and crystals.
mineral
Lindi Garnet
Lindi Garnet is a rare vanadium-rich color-change garnet from Tanzania's Lindi region, shifting from blue-green daylight tones to purple-red.
gemstone
White Moonstone
The classic moonstone: a milky-white feldspar showing the prized floating blue-to-silver adularescent glow that gives the gem its name.
gemstone
Phantom Quartz
Quartz containing visible internal crystal outlines, formed when growth paused and trapped a layer of mineral inclusions.
crystal
Matrix Opal
Opal in which precious play-of-color is intimately dispersed through the pores of its host rock rather than forming a solid seam.
gemstone