Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Cipollino Marble
A green-and-white banded metamorphic marble whose wavy mica layers resemble the rings of a sliced onion.
metamorphic
Kakortokite
A spectacularly banded agpaitic nepheline syenite of alternating red eudialyte, black amphibole and white feldspar layers from Ilimaussaq, Greenland.
igneous
Onyx
A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.
gemstone
Black Moonstone
A dark gray-to-black feldspar variety of moonstone that shows blue and white adularescent flash against a smoky body.
gemstoneCloud Agate
A chalcedony agate with soft, billowing cloud-like masses of gray and white suspended in a translucent body.
gemstone
Andradite Garnet
The calcium-iron garnet species, ranging from brilliant green demantoid to golden topazolite and jet-black melanite.
gemstone
Brazilian Opal
Precious opal from Brazil, especially the Pedro II area of Piaui, known for bright, often stable crystal and white opal.
gemstone
Larimar
A rare sky-blue variety of pectolite found only in the Dominican Republic, prized for its sea-like color and white volcanic patterning.
gemstone
Andesine-Labradorite
An intermediate plagioclase feldspar spanning andesine and labradorite, marketed as a red-to-green gem, much of which is copper-diffusion treated.
gemstone
Wolframite
Wolframite is the historic principal ore of tungsten, a heavy black tungstate forming bladed crystals in granite veins.
mineral
Rhyolite
A fine-grained, silica-rich volcanic rock that is the extrusive equivalent of granite, often pale, banded, or flow-textured.
igneous
Orthoclase
A common rock-forming potassium feldspar, the Mohs hardness reference at 6, found in granites and used in ceramics and glassmaking.
mineral
Feldspar
The most abundant mineral group in Earth's crust, feldspars are aluminosilicates that form much of granite and many igneous rocks.
mineral
Rubicline
An extremely rare rubidium-dominant alkali feldspar, the rubidium analogue of microcline, found in rare-element granitic pegmatites.
mineral
Snow Quartz
An opaque, snow-white variety of quartz whose milky color comes from countless tiny gas and fluid inclusions.
crystal
Milky Quartz
The most common variety of quartz, milky white from microscopic fluid and gas inclusions, forming massive veins worldwide.
crystal
Rose Tourmaline
A soft to medium pink elbaite tourmaline in rose hues, colored by manganese and prized for romantic jewelry.
gemstone
Goshenite
The colorless variety of beryl, named after Goshen, Massachusetts, prized for its purity, clarity, and durability.
gemstoneCat's Eye Morganite
Pink beryl (morganite) that shows chatoyancy, a moving band of light, when cut as a cabochon, thanks to parallel tube inclusions.
gemstone
Sylvanite
A silver-white gold-silver telluride and important gold-silver ore, noted for crystals arranged in writing-like graphic patterns.
mineral
Topaz
A hard, brilliant fluorosilicate gemstone occurring in many colors, from precious golden imperial topaz to popular blue topaz.
gemstone
Magnesite
A magnesium carbonate mineral, usually chalky white with grey veining, widely dyed to imitate turquoise and other stones.
mineral
Cherry Opal
A translucent red opal, closely related to Mexican fire opal, glowing with a warm cherry-red body color often free of play-of-color.
gemstoneAlabaster
A soft, fine-grained, translucent form of gypsum (or banded calcite) long prized as a carving and ornamental stone.
mineral