Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Pyrargyrite
A silver antimony sulfosalt known as dark ruby silver, an important silver ore with deep red internal reflections.
mineral
Anglesite
A heavy lead sulfate secondary mineral, often colorless to white with adamantine luster, formed by the oxidation of galena.
mineral
Franklinite
A black spinel-group zinc iron oxide, essentially unique to Franklin, New Jersey, where it was a key zinc and manganese ore.
mineral
Proustite
A scarlet-red silver arsenic sulfide known as light ruby silver, a striking but light-sensitive ore that darkens on exposure.
mineral
Siderite
Siderite is an iron carbonate ore, a brown rhombohedral mineral of the calcite group found in sediments and veins.
mineral
Kimberlite
A rare ultramafic volcanic rock that erupts from deep in the mantle and is the primary natural source of diamonds.
igneous
Azurite
A deep blue copper carbonate mineral that forms in oxidized copper deposits, often alongside green malachite.
mineral
Calaverite
A brass- to silver-yellow gold telluride that is a major gold ore, famous from Cripple Creek and Kalgoorlie.
mineral
Sperrylite
A rare platinum arsenide and the most important platinum-bearing mineral, forming bright metallic cubic crystals.
mineral
Sylvanite
A silver-white gold-silver telluride and important gold-silver ore, noted for crystals arranged in writing-like graphic patterns.
mineral
Crocoite
A striking lead chromate mineral prized for its brilliant orange-red prismatic crystals, with the finest specimens from Tasmania.
mineral
Biggs Jasper
A classic Oregon picture jasper showing layered tan, brown, and blue-grey scenes resembling desert landscapes and canyons.
mineralRogue River Jasper
An Oregon picture jasper from the Rogue River area showing earthy scenic patterns in tan, brown, gold, and cream.
mineral
Wolframite
Wolframite is the historic principal ore of tungsten, a heavy black tungstate forming bladed crystals in granite veins.
mineral
Stibnite
Stibnite is the chief ore of antimony, famous for its dramatic clusters of bladed, silvery-gray metallic crystals.
mineral
Skarn
A calc-silicate rock formed by chemical exchange between magma and carbonate rock, often rich in garnet and economically important ore minerals.
metamorphic
Lamproite
A rare ultrapotassic, magnesium-rich volcanic rock from deep in the mantle, famous as the diamond host at Argyle in Australia.
igneous
Acanthite
A silver sulfide that is one of the most important silver ore minerals, forming dark metallic crystals and wires.
mineral
Niccolite
A pale copper-red nickel arsenide, historically called kupfernickel, that is an ore of nickel and gives the metal its name.
mineral
Cassiterite
Tin oxide and the principal ore of tin, a dense, hard mineral mined since the Bronze Age for tin metal.
mineralCarver Agate
A collectible Oregon plume and scenic agate with feathery red and gold inclusions suspended in translucent chalcedony.
gemstone
Owyhee Jasper
A picture jasper from the Owyhee region of Oregon and Idaho, prized for scenic tan, cream, and blue-grey landscape patterns.
mineral
Tactite
A contact-metasomatic calc-silicate rock, essentially a skarn, formed where intrusions react with carbonate rocks and often host ore.
metamorphic
Ilmenite
Ilmenite is the world's leading source of titanium, a heavy iron-black oxide common in mafic rocks and black sands.
mineral