Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Sard
A brownish-red to deep brown variety of chalcedony, closely related to carnelian but darker, colored by iron oxides.
mineral
Crocodile Jasper
A deep green-and-black stromatolitic jasper, essentially Kambaba Jasper, with circular eye patterns resembling crocodile skin.
mineral
Orange Calcite
A soft, glowing orange variety of calcite colored by iron oxides, popular as tumbled stones and known for fizzing in acid.
mineral
Carnelian
A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.
gemstone
Red Agate
A red-toned banded chalcedony colored by iron oxides, ranging from natural carnelian-like reds to heat-treated stones.
gemstone
Picture Jasper
An opaque brown chalcedony whose iron-stained banding mimics deserts, dunes, and distant mountain skylines.
mineral
Orange Obsidian
Obsidian colored orange by iron oxide inclusions; vivid uniform orange material is frequently manufactured glass rather than volcanic.
igneous
Kambaba Jasper
A dark green-and-black stromatolite jasper patterned with swirling orbs, formed from fossilized ancient microbial colonies.
sedimentary
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
Pumpkin Obsidian
An orange-to-rust colored variety of natural volcanic glass whose warm tone comes from iron oxide staining within the obsidian.
igneous
Ribbon Jasper
A banded jasper showing parallel ribbon-like stripes of contrasting color formed by layered silica and mineral deposition.
mineral
Cherry Creek Jasper
A landscape-patterned Chinese jasper prized for warm cherry-red, cream, and green bands resembling painted scenery.
mineral
Tangerine Quartz
Clear quartz coated with orange-red hematite, giving points a vivid tangerine color, mainly from Brazil.
crystal
Koroit Opal
Boulder opal from the Koroit field in Queensland, famous for intricate ironstone matrix patterns laced with colorful precious opal.
gemstone
Tantalite
A dense black iron-manganese tantalate that is the chief ore of tantalum, forming a series with columbite and mined as coltan.
mineral
Boulder Opal
Precious opal that forms in thin veins within brown ironstone boulders, cut with the host rock left as a natural dark backing.
gemstone
Columbite
A black iron-manganese niobate that is a primary ore of niobium, forming a continuous series with tantalite (together called coltan).
mineral
Black Tourmaline
The opaque black iron-rich variety of tourmaline (schorl), forming striated prismatic crystals popular as a protective grounding stone.
mineral
Red Jasper
An opaque, iron-rich variety of microcrystalline quartz known for its deep brick-red color and ancient history as a stone of strength and grounding.
gemstone
Pyrite
The brassy iron sulfide mineral famous as 'fool's gold,' known for sharp metallic cubes and a much higher hardness than real gold.
mineral
Schorl
The common iron-rich black variety of tourmaline, by far the most abundant tourmaline species and a popular grounding crystal.
mineral
Blue Beryl
The blue color variety of beryl, ranging from pale sky tones to rich sea-blue, best known in its finest grades as aquamarine.
gemstone
Yowah Nut Opal
Small ironstone concretions from Yowah, Queensland, whose hollow or veined centers hold brilliant precious boulder opal.
gemstone
Yellow Beryl
The yellow variety of beryl, also called heliodor or golden beryl, colored by iron and valued for its bright color and durability.
gemstone