Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Bird's Eye Jasper
A microcrystalline quartz jasper marked by small concentric ring or eye patterns that resemble the eyes of birds.
mineral
Cave Creek Jasper
An opaque jasper from the Cave Creek area of Arizona, prized for earthy mottled and banded patterns in warm desert tones.
mineral
Kambaba Jasper
A dark green-and-black stromatolite jasper patterned with swirling orbs, formed from fossilized ancient microbial colonies.
sedimentary
Ribbon Jasper
A banded jasper showing parallel ribbon-like stripes of contrasting color formed by layered silica and mineral deposition.
mineral
Fire Agate
A rare brown chalcedony containing thin iron-oxide layers that produce flashing, fiery rainbow iridescence like trapped flames.
gemstone
Cherry Creek Jasper
A landscape-patterned Chinese jasper prized for warm cherry-red, cream, and green bands resembling painted scenery.
mineral
Phyllite
A fine-grained foliated metamorphic rock between slate and schist, recognized by its silky silvery sheen and wavy, crinkled surfaces.
metamorphic
Argillite
Hardened, fine-grained mudrock intermediate between shale and slate, dense and non-fissile, often carved into ornaments.
sedimentary
Tangerine Quartz
Clear quartz coated with orange-red hematite, giving points a vivid tangerine color, mainly from Brazil.
crystal
Koroit Opal
Boulder opal from the Koroit field in Queensland, famous for intricate ironstone matrix patterns laced with colorful precious opal.
gemstone
Bixbyite
A black metallic manganese iron oxide famous for sharp cubic crystals, classically found with red beryl and topaz in Utah rhyolite.
mineral
Tantalite
A dense black iron-manganese tantalate that is the chief ore of tantalum, forming a series with columbite and mined as coltan.
mineral
Red Obsidian
Volcanic glass tinted red by fine iron-oxide inclusions, often blended with black to form mahogany-patterned obsidian.
crystal
Boulder Opal
Precious opal that forms in thin veins within brown ironstone boulders, cut with the host rock left as a natural dark backing.
gemstone
Columbite
A black iron-manganese niobate that is a primary ore of niobium, forming a continuous series with tantalite (together called coltan).
mineral
Black Tourmaline
The opaque black iron-rich variety of tourmaline (schorl), forming striated prismatic crystals popular as a protective grounding stone.
mineral
Red Jasper
An opaque, iron-rich variety of microcrystalline quartz known for its deep brick-red color and ancient history as a stone of strength and grounding.
gemstone
Pyrite
The brassy iron sulfide mineral famous as 'fool's gold,' known for sharp metallic cubes and a much higher hardness than real gold.
mineral
Schorl
The common iron-rich black variety of tourmaline, by far the most abundant tourmaline species and a popular grounding crystal.
mineral
Chromite
Chromite is the only commercial ore of chromium, a black iron-chromium oxide of the spinel group found in mafic igneous rocks.
mineral
Blue Beryl
The blue color variety of beryl, ranging from pale sky tones to rich sea-blue, best known in its finest grades as aquamarine.
gemstone
Yowah Nut Opal
Small ironstone concretions from Yowah, Queensland, whose hollow or veined centers hold brilliant precious boulder 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
Pyrrhotite
A bronze-colored iron sulfide notable for being the most magnetic of the common sulfide minerals and an important nickel host.
mineral