Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Lake Huron Agate

Glacially transported banded agates found along Lake Huron's shores, typically small, frosted pebbles with red-orange iron banding.

A fine-grained, sodium-rich contact-metasomatic rock formed where shale is albitized next to intruding diabase or spilite.

A distinctive tourmaline-rich granite from Cornwall, prized as an ornamental stone for its pink feldspar set with radiating black tourmaline.

A translucent chalcedony from Montana filled with black and red dendritic inclusions that look like moss, ferns, or scenic landscapes.

A group of silicate gemstones best known for deep red but spanning nearly every color, including green tsavorite and orange spessartine.

A translucent agate containing delicate three-dimensional feather- or plant-like plumes of mineral inclusions suspended in chalcedony.

A glassy calcium borosilicate forming wedge-tipped prismatic crystals, usually colorless to pale yellow or pink, sometimes faceted as a gem.

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.

Aquamarine crystals still attached to their natural host rock, prized as mineral specimens showing beryl in its original pocket setting.

An old name for a dull leek-green variety of quartz or chalcedony colored by green mineral inclusions, historically called mother of emerald.

A pale, nepheline-dominated plutonic rock at the leucocratic end of the ijolite series, sometimes associated with major apatite ore deposits.

A tourmaline displaying two or more distinct colors in a single crystal, prized for natural color zoning like watermelon and bicolor stones.