Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Bytownite
A calcium-rich plagioclase feldspar between labradorite and anorthite, faceted as transparent golden-yellow gems sometimes sold as yellow labradorite.
gemstone
Shonkinite
A dark, mafic potassic alkaline rock rich in augite with alkali feldspar and often nepheline, classically forming the base of layered sills.
igneous
Ijolite
A coarse-grained, feldspar-free plutonic rock composed mainly of nepheline and sodic pyroxene, the intrusive equivalent of nephelinite.
igneous
Millerite
A nickel sulfide famous for delicate brass-yellow hairlike crystals that form radiating sprays inside cavities and geodes.
mineralDragon Vein Agate
A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.
gemstone
Iris Agate
A banded agate that diffracts transmitted light into rainbow colors when cut thin and backlit, producing a spectacular iridescence.
gemstoneLeopard Obsidian
Black volcanic glass marked with rounded spots and patches that resemble a leopard's coat, caused by spherulitic crystallization.
igneous
Feruvite
A calcium- and ferrous-iron-rich tourmaline, the iron analogue of uvite, forming dark brown to black crystals in skarns and metamorphic rocks.
mineral
Scenic Jasper
A patterned jasper whose bands and inclusions create miniature landscapes of deserts, mountains, and skies within the stone.
mineral
Crocodile Jasper
A deep green-and-black stromatolitic jasper, essentially Kambaba Jasper, with circular eye patterns resembling crocodile skin.
mineral
Harzburgite
A depleted mantle peridotite of olivine and orthopyroxene, the refractory residue left after basaltic melt is extracted from the mantle.
igneous
Rubellite
The red to raspberry-pink variety of tourmaline, prized for its vivid ruby-like color that holds under both daylight and artificial light.
gemstone
Lime Green Tourmaline
A bright, fresh lime to yellowish-green elbaite tourmaline (verdelite), colored by iron and trace manganese for a lively spring-green tone.
gemstone
Blue Kyanite
A striking blue aluminum silicate famous for bladed crystals and anisotropic hardness that differs dramatically along and across the blade.
mineral
Clear Quartz
The pure, colorless form of crystalline quartz, valued for its clarity, abundance, and piezoelectric properties used in electronics.
crystal
Madagascar Jasper
A broad family of vividly patterned jaspers from Madagascar, including orbicular and scenic varieties prized for colorful, eye-catching designs.
gemstone
Essexite
A dark, silica-undersaturated gabbroic rock containing nepheline along with plagioclase, alkali feldspar, and pyroxene, also known as nepheline monzogabbro.
igneous
Rainbow Velvet Obsidian
A natural sheen obsidian whose black glass displays a soft, velvety rainbow shimmer from aligned magnetite nanoparticles when polished and tilted.
igneousNaujaite
A sodalite-rich agpaitic nepheline syenite with poikilitic texture from the Ilimaussaq complex, packed with blue sodalite, eudialyte and arfvedsonite.
igneous
Kersantite
A dark mica lamprophyre with biotite and augite phenocrysts in a plagioclase-dominated groundmass, the feldspar counterpart of minette.
igneous
Palagonite
A yellow-brown alteration material formed when basaltic volcanic glass reacts with water, common in hydrovolcanic tuffs and pillow lavas.
igneousPeanut Wood Jasper
A fossilized, silicified wood from Australia with white peanut-shaped spots, formed where ancient driftwood was bored by clams and filled with pale sediment.
gemstone
Kunzite
The delicate pink-to-lilac variety of spodumene, a lithium silicate prized for soft color and strong pleochroism but tricky perfect cleavage.
gemstone
Gahnite
A hard zinc-rich member of the spinel group, usually dark blue-green to black, forming octahedral crystals in metamorphic and pegmatitic rocks.
mineral