Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Color-Change Tourmaline
A rare tourmaline that visibly changes color between daylight and incandescent light, similar to the alexandrite effect.
gemstone
Carbonatite
A rare igneous rock made mostly of carbonate minerals, source of the world's most important rare-earth-element and niobium deposits.
igneous
Amethyst
The purple variety of quartz, colored by iron and natural irradiation, prized as the classic violet birthstone of February.
crystal
Galena
A heavy, lead-grey metallic mineral with perfect cubic cleavage, galena is the world's main ore of lead and often carries silver.
mineral
Mookaite Jasper
An Australian silicified radiolarite jasper in warm mustard, red, burgundy, and cream earth tones, found only in Western Australia.
sedimentary
Elestial Quartz
A quartz with a complex skeletal, layered surface of many terminations and etched recesses, also called skeletal or jacare quartz.
crystal
Yttrium Aluminum Garnet
A synthetic garnet-structured oxide (YAG) used as a diamond simulant and laser crystal, with no natural counterpart.
gemstone
Hessonite Garnet
The cinnamon-to-honey colored variety of grossular garnet, prized in jewelry and revered as the gem 'gomed' in Vedic astrology.
gemstone
Platinum
A dense, durable, silvery-white precious metal that resists corrosion, used in fine jewelry and catalytic converters.
mineral
Opalite
A man-made opalescent glass that glows milky blue in reflected light and warm orange when backlit, often sold as a crystal.
crystal
Tachylite
An opaque, iron-rich basaltic volcanic glass formed by the rapid chilling of basalt lava, darker and denser than rhyolitic obsidian.
igneous
Cave Creek Jasper
An opaque jasper from the Cave Creek area of Arizona, prized for earthy mottled and banded patterns in warm desert tones.
mineral
Black Opal
The rarest and most valuable opal, with a dark body tone that makes its flashing rainbow play-of-color blaze brilliantly.
gemstone
Lujavrite
A dark, layered agpaitic nepheline syenite rich in sodic pyroxene and amphibole with eudialyte, from the Lovozero and Ilimaussaq complexes.
igneous
Lead Feldspar
A very rare lead-dominant feldspar composition, the lead analogue of anorthite, known largely from synthetic studies and lead-rich environments.
mineral
Spherulitic Obsidian
Obsidian containing spherulites — small radiating spheres of feldspar and cristobalite that crystallized within the cooling volcanic glass.
igneousGreen Jade
The classic green ornamental gem, either jadeite or nephrite, valued for millennia for its toughness and rich color, especially imperial green.
gemstone
Potassium Feldspar
The potassium-rich feldspar group - orthoclase, microcline, and sanidine - a major rock-forming mineral often recognized by its salmon-pink color.
mineral
Sinter
A chemical deposit precipitated around hot springs and geysers, either siliceous (geyserite) or calcareous, forming delicate terraces and crusts.
sedimentary
Chrysoberyl
An exceptionally hard beryllium aluminum oxide prized for golden hues, sharp cat's-eye effect, and the rare color-change alexandrite variety.
gemstoneMacusanite
A rare translucent yellow-green volcanic glass from the Macusani region of Peru, valued by faceters and sometimes confused with tektites.
igneousWoodbine Jasper
An earthy-toned jasper with vine-like or scenic patterning, valued by lapidaries for warm browns, reds, and creams that polish to a smooth finish.
gemstone
Montana Moss Agate
A translucent chalcedony from Montana filled with black and red dendritic inclusions that look like moss, ferns, or scenic landscapes.
gemstone
Flower Agate
A creamy pink-and-white chalcedony from Madagascar containing flower-like plume inclusions that resemble blossoms suspended in stone.
gemstone