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The mineral atlas
Explore the wider assortment of rock assemblages, impact glasses, silica materials and collector minerals. These entries explain such names as indigo gabbro, Dalmatian stone and fairy crosses through their actual constituents, textures or crystal intergrowths.
20 specimens · Geology, history, and spiritual attributes
20 specimens
Hydrated Silica, Moving Color and Preserved Worlds
Hydrated silica material; precious opal shows play-of-color and common opal does not.
Opal can carry shifting spectral color, a quiet milky translucency or a rich brown body with no rainbow at all.
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Earthly Glass from an Extraordinary Impact
Natural impact-generated glasses derived from terrestrial material.
Moldavite is associated with a collision from space, but its glass is transformed terrestrial material—not a green fragment of the incoming meteorite.
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Pink feldspar and green epidote in an altered granitic rock
Altered rock combining feldspar, epidote and commonly quartz.
Unakite's pink-and-green pattern belongs to a rock assembled from contrasting minerals.
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A pale feldspar-rich rock patterned with dark amphibole spots
Spotted ornamental rock; analyzed trade samples contain a feldspar-quartz matrix with arfvedsonite-rich dark areas.
Dalmatian stone is recognized by the contrast between its light groundmass and scattered dark spots.
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Green Orbicular Volcanic Rock
Green-and-black orbicular rhyolitic rock in the documented trade material.
Kambaba stone's dark rings and olive-green ground make it distinctive.
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Silica-Rich Volcanic Rock
Silica-rich volcanic rock, with varied textures and mineral mixtures.
Rhyolite is a volcanic rock whose composition is rich in silica.
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A Coarse-Grained Igneous Rock
Gabbro is a coarse-grained mafic igneous rock; indigo gabbro is a trade label.
Gabbro is a dark, coarse-grained rock formed as mafic magma crystallizes below the surface.
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Bronzy Iron-Bearing Orthopyroxene
Bronzy-shimmering orthopyroxene material associated with the enstatite–ferrosilite series.
Bronzite names iron-bearing enstatite with a bronze-like reflection.
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A Legacy Name for Iron-Bearing Orthopyroxene
Legacy name within the enstatite–ferrosilite series, retained in gem trade.
Hypersthene is a historical name for iron-bearing orthopyroxene, now classified within the enstatite–ferrosilite series.
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An Amphibole Rock with Hidden Iridescence
Iridescent amphibole-bearing metamorphic rock associated with Nuuk, Greenland.
Nuummite is a dark ornamental rock whose polished surface can reveal narrow flashes of gold, bronze, blue or violet.
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Bronze Blades in Pale Stone
Titanium-bearing silicate mineral with often radiating golden-brown blades.
Astrophyllite is a titanium-bearing silicate best known for bronze and golden-brown blades that spread through a contrasting host rock.
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A Dark Amphibole with a Complex Interior
Sodium-rich amphibole mineral commonly in alkaline igneous rocks.
Arfvedsonite is a sodium-iron amphibole found in alkaline igneous rocks.
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Clear Geometry in Mineral-Lined Cavities
A group of hydrous silicate minerals.
Apophyllite names a group of hydrated silicates whose reflective, blocky or pointed crystals often line mineral cavities.
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Open Frameworks, Fans and Fine Crystal Sprays
A family of hydrated aluminosilicates; species differ.
Zeolites are a family of minerals, not one stone with one formula.
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A Borosilicate of Clear Crystals and Quiet Color
Calcium borosilicate mineral.
Danburite occupies an interesting space between mineral cabinet and jewelry case.
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Salt Crystals, Vanished Waters and Preserved History
Sodium chloride mineral, occurring in evaporite deposits.
Halite is sodium chloride in mineral form.
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Blue Pectolite from the Dominican Republic
Blue pectolite trade material from the Dominican Republic.
Larimar's blue-and-white pattern can resemble light moving over shallow water.
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A Gem with a History Beyond Ruby
Magnesium aluminium oxide mineral.
Spinel does not need to borrow another gemstone's reputation.
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Natural Crosses in Metamorphic Rock
Iron-rich aluminium silicate, sometimes naturally twinned into cross-like forms.
Staurolite's crossed crystals are among the most recognizable shapes in a mineral collection.
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Carbonate, Sulfide Pigments and Striking Bands
Carbonate-rich Indonesian decorative rock, despite the common jasper label.
Bumblebee stone takes its trade name from the contrast of yellow, orange, gray and black.
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