Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Tholeiitic Basalt
The most abundant basalt type on Earth, a silica-saturated subalkaline lava that forms ocean crust and flood basalts.
igneous
Smithsonite
Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.
mineral
Sapphire
The gem variety of corundum in every color except red, most prized in velvety blue and exceptionally hard and durable.
gemstone
Rose Tourmaline
A soft to medium pink elbaite tourmaline in rose hues, colored by manganese and prized for romantic jewelry.
gemstone
Pink Agate
A soft pink banded chalcedony, occurring naturally in delicate hues and also commonly produced by dyeing.
gemstone
Peacock Opal
A precious opal showing dominant peacock-like blue, green and teal play-of-color, often on Ethiopian material.
gemstone
Owyhee Blue Agate
A soft sky-blue chalcedony from the Owyhee region of Oregon and Idaho, prized for its calming, opaque powder-blue color.
gemstone
Menilite Opal
An opaque grey-brown common opal forming nodules and concretions, historically called liver opal for its dull brownish color.
mineral
Indicolite
The blue variety of tourmaline, a relatively rare and prized color ranging from teal and greenish blue to deep indigo.
gemstone
Kentucky Agate
The official state rock of Kentucky, a banded agate famous for striking deep-red and black fortification patterns.
gemstone
Faden Quartz
Tabular quartz crossed by a milky white thread-like line marking where the crystal repeatedly cracked and re-healed.
crystal
Exotica Jasper
Also called Sci-Fi Jasper, a Mexican jasper-rhyolite with swirling abstract patterns in cream, tan, gray, pink, and green.
gemstone
Crystal Opal
Precious opal with a transparent or translucent body, letting play-of-color glow with exceptional depth and clarity.
gemstone
Coquina
A soft, porous limestone made of loosely cemented shell and coral fragments, used as a coastal building stone.
sedimentary
Cloud Agate
A chalcedony agate with soft, billowing cloud-like masses of gray and white suspended in a translucent body.
gemstone
Alnöite
A rare dark ultramafic lamprophyre rich in melilite, biotite and olivine, named for Alnö Island in Sweden.
igneous
Brazilian Opal
Precious opal from Brazil, especially the Pedro II area of Piaui, known for bright, often stable crystal and white opal.
gemstone
Yellow Beryl
The yellow variety of beryl, also called heliodor or golden beryl, colored by iron and valued for its bright color and durability.
gemstone
Wyomingite
A rare ultrapotassic lamproite of leucite, phlogopite and diopside, named for and typified by Wyoming's Leucite Hills.
igneous
Syrian Garnet
Syrian Garnet is an old trade name for fine deep-red almandine, historically tied to the Syriam region and prized as 'precious garnet.'
gemstone
Sunset Agate
A warmly colored chalcedony agate with reds, oranges, golds, and pinks that blend like the glowing bands of a sunset sky.
gemstone
Red Beryl
An exceptionally rare red variety of beryl colored by manganese, found chiefly in Utah and prized as one of the rarest gems.
gemstone
Rogue River Jasper
An Oregon picture jasper from the Rogue River area showing earthy scenic patterns in tan, brown, gold, and cream.
mineral
Rhodochrosite
Rhodochrosite is a rose-pink manganese carbonate prized for raspberry-red crystals and banded pink-and-white gem material.
gemstone