Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Metaconglomerate
A conglomerate altered by heat and pressure, often with its rounded pebbles stretched and flattened into elongated lenses.
metamorphic
Charnockite
A granite-like rock containing orthopyroxene, formed at high temperatures and pressures and often classed with the granulites.
igneous
Mustard Jasper
A warm mustard-to-ochre yellow jasper colored by iron, valued by lapidaries for its rich, earthy golden tone.
gemstone
Anhydrite
A water-free calcium sulfate mineral closely related to gypsum, forming in evaporite deposits and swelling into gypsum when it absorbs water.
mineralDragon Blood Jasper
A green-and-red ornamental stone of epidote and red piemontite or iron oxide, named for its dragon-skin coloring; not a true jasper.
metamorphic
Graphic Feldspar
A pegmatite rock of feldspar intergrown with wedge-shaped quartz that resembles ancient runic or Hebrew writing.
igneous
Metabasalt
Basalt that has been metamorphosed, developing new minerals like chlorite, actinolite, and epidote that give it a greenish color.
metamorphic
Aquamarine Matrix
Aquamarine crystals still attached to their natural host rock, prized as mineral specimens showing beryl in its original pocket setting.
mineral
Metagabbro
Coarse-grained gabbro that has been metamorphosed, partly recrystallizing into amphibole, plagioclase, and other metamorphic minerals.
metamorphic
Brecciated Agate
Agate that was shattered and naturally re-cemented by silica, creating a mosaic of angular fragments in a quartz matrix.
gemstone
Calc-schist
A foliated metamorphic rock of calcite mixed with mica, quartz, and calc-silicate minerals, derived from marly sediments.
metamorphic
Bumblebee Jasper
A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.
sedimentary
Bronzite
An iron-rich orthopyroxene prized for its warm bronze schiller, a metallic-looking sheen created by tiny mineral inclusions.
mineral
Pink Emerald
A trade name sometimes used for pink beryl (morganite), the manganese-colored rose-to-peach variety of the emerald mineral.
gemstone
Trachyte
A fine-grained volcanic rock dominated by alkali feldspar, the extrusive equivalent of syenite.
igneousRainforest Jasper
An Australian green rhyolite with eye-like orbs and earthy patterns marketed as jasper, evoking dense rainforest foliage.
igneous
Chrysoprase
A translucent apple-green chalcedony colored by nickel, the most prized green variety of the quartz family.
gemstone
Golden Emerald
A trade name occasionally used for golden-yellow beryl (golden beryl or heliodor), the iron-colored yellow variety of the emerald mineral.
gemstone
Thulite
A pink, manganese-rich variety of zoisite used as an ornamental gemstone, often mottled with white quartz and grey matrix.
gemstoneSlate
A fine-grained, low-grade metamorphic rock that splits into flat sheets along slaty cleavage, long used for roofing and flooring.
metamorphicStarburst Agate
Agate containing radiating sprays of mineral needles that fan out like bursting stars within the chalcedony.
gemstone
Black Shale
Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.
sedimentary
Landscape Agate
A translucent chalcedony agate whose mineral inclusions form miniature scenes resembling mountains, trees, deserts, and skies.
gemstone
Tube Agate
A chalcedony agate containing hollow or mineral-filled tubes that appear as rods, circles, or pipes depending on the angle of the cut.
gemstone