Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Tetrahedrite
A gray copper-antimony sulfosalt of the fahlore group, an important ore of copper and often silver, forming tetrahedral crystals.
mineral
Stibnite
Stibnite is the chief ore of antimony, famous for its dramatic clusters of bladed, silvery-gray metallic crystals.
mineral
Chrysoprase
A translucent apple-green chalcedony colored by nickel, the most prized green variety of the quartz family.
gemstone
Pietersite
A brecciated, chatoyant quartz with swirling blue, gold, and brown fibers that shimmer like a stormy sky.
gemstone
Australian Opal
Opal from Australia, the world's leading source of precious opal, ranging from white and crystal to prized black and boulder types.
gemstone
Obsidian
A glassy, jet-black volcanic rock formed when lava cools too fast to crystallize, prized for razor-sharp conchoidal edges.
igneous
Buergerite
A rare iron-rich (ferric) species of the tourmaline group, dark brown to bronze-black, named after crystallographer Martin Buerger.
mineral
Clear Beryl
Transparent, colorless beryl (goshenite), the pure form of the species valued for its clarity, hardness, and well-formed crystals.
gemstone
Uvarovite Garnet
The rare calcium-chromium garnet, famous for its sparkling emerald-green druzy crusts of tiny crystals, the only consistently green garnet.
mineralBird's Eye Jasper
A microcrystalline quartz jasper marked by small concentric ring or eye patterns that resemble the eyes of birds.
mineral
Acanthite
A silver sulfide that is one of the most important silver ore minerals, forming dark metallic crystals and wires.
mineral
Sperrylite
A rare platinum arsenide and the most important platinum-bearing mineral, forming bright metallic cubic crystals.
mineral
Celestite
A soft, sky-blue strontium sulfate mineral famous for the glittering pale-blue crystal geodes from Madagascar.
mineral
Blue Pearl Granite
A Norwegian larvikite dimension stone prized for its shimmering blue iridescent feldspar crystals.
igneous
Chalcocite
A dark gray copper sulfide that is one of the richest copper ores, prized by collectors when found as rare sharp crystals.
mineral
Danburite
A glassy calcium borosilicate forming wedge-tipped prismatic crystals, usually colorless to pale yellow or pink, sometimes faceted as a gem.
crystal
Foitite
A rare alkali-deficient tourmaline whose X crystal site is largely vacant, giving slender dark blue to bluish-black crystals.
mineral
Hemimorphite
A hydrous zinc silicate, often sky-blue, that is an ore of zinc and a collectible mineral forming botryoidal crusts and crystals.
mineral
Onyx
A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.
gemstone
Snowflake Obsidian
A black volcanic glass speckled with gray-white cristobalite snowflakes, formed as obsidian begins to crystallize.
igneous
Watermelon Tourmaline
A striking color-zoned tourmaline with a pink center and green rind, resembling a slice of watermelon when cut across the crystal.
gemstone
Cerussite
A dense lead carbonate mineral forming brilliant colorless to white crystals, an important ore of lead and a favorite of collectors.
mineral
Yttrium Aluminum Garnet
A synthetic garnet-structured oxide (YAG) used as a diamond simulant and laser crystal, with no natural counterpart.
gemstone
Cobaltite
A silver-white cobalt arsenic sulfide that is a leading ore of cobalt, forming bright metallic cubic and pyritohedral crystals.
mineral