Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Magnetite
A naturally magnetic black iron oxide and a major iron ore; strongly magnetic specimens are known as lodestone.
mineral
Lepidolite
A soft lithium-bearing mica with a lilac to purple color and pearly, flaky sheen, an important ore of lithium.
mineral
Orange Tourmaline
A warm orange to tangerine tourmaline, an uncommon hue produced by manganese and iron in the crystal.
gemstone
Botswana Agate
A finely banded agate from Botswana known for delicate parallel layers of grey, pink, and white.
mineral
Diabase
A tough, dark, medium-grained igneous rock with the composition of basalt, common in dikes and sills.
igneous
Sulfur
A bright yellow native element mineral that forms around volcanic vents and hot springs and burns with a blue flame.
mineral
Mandarin Garnet
The intensely glowing orange variety of spessartine garnet, prized for its pure 'Fanta-orange' fire and high brilliance.
gemstone
Soapstone
A soft, talc-rich metamorphic rock with a soapy feel, easily carved and highly heat-resistant for cookware and sculpture.
metamorphicMadagascar Opal
Opal from Madagascar spanning colorful common opal and some precious opal, including pink, green and boulder-type material.
gemstone
Blue Goldstone
A man-made glittering glass colored deep blue with cobalt and studded with tiny copper crystals that mimic a starry night sky.
gemstone
Schorl
The common iron-rich black variety of tourmaline, by far the most abundant tourmaline species and a popular grounding crystal.
mineralLeuco Garnet
The rare colorless variety of grossular garnet, a near-flawless transparent gem free of the iron and chromium that color most garnets.
gemstone
Blue Apatite
A blue calcium phosphate mineral with vivid color and middling hardness, the same mineral family that forms bones and teeth.
mineral
Welo Opal
Bright play-of-color opal from the Wollo Province of Ethiopia, mostly hydrophane and known for broad, vivid fire.
gemstone
Malachite
A vivid green copper carbonate mineral famous for swirling concentric bands, used as an ore of copper and an ornamental gemstone.
mineral
Bituminous Coal
A dense, black, mid-rank coal with high energy content, widely used for power generation and to make coke for steelmaking.
sedimentary
Troctolite
A mafic plutonic rock of plagioclase and olivine whose mottled appearance earned it the nickname 'troutstone'.
igneous
Ruby in Zoisite
A striking rock of green zoisite studded with red-pink ruby crystals and black hornblende, also called anyolite.
metamorphic
Tantalite
A dense black iron-manganese tantalate that is the chief ore of tantalum, forming a series with columbite and mined as coltan.
mineral
Sylvanite
A silver-white gold-silver telluride and important gold-silver ore, noted for crystals arranged in writing-like graphic patterns.
mineral
Kimberlite
A rare ultramafic volcanic rock that erupts from deep in the mantle and is the primary natural source of diamonds.
igneous
Hausmannite
A brownish-black manganese oxide and important manganese ore, forming pseudo-octahedral crystals with a chestnut-brown streak.
mineral
Serpentine
A group of green magnesium silicate minerals with a smooth, waxy feel, often carved and sometimes sold as imitation jade.
mineral
Calcrete
Carbonate-cemented soil crust formed in arid regions where calcium carbonate accumulates and hardens within the regolith.
sedimentary