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 Superior Agate

A glacier-transported banded agate from the Lake Superior region, colored by iron into rich reds and oranges, and Minnesota's state gemstone.

A white to grayish banded chalcedony, the natural base color of much agate and the substrate for many dyed stones.

A patterned common opal with mottled, leopard-like spots and blotches, prized as an ornamental and cabochon stone.

A soft, fine-grained, translucent form of gypsum (or banded calcite) long prized as a carving and ornamental stone.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

A spectacularly banded agpaitic nepheline syenite of alternating red eudialyte, black amphibole and white feldspar layers from Ilimaussaq, Greenland.

A translucent agate whose mineral inclusions resemble miniature landscapes of trees, hills, and horizons within the stone.

Precious opal from the Mintabie field in South Australia, known for hard, bright crystal opal and some dark-bodied stones.

An affordable multicolored banded and mossy chalcedony from India, common in tumbled stones, beads, and meditation pieces.

A plagioclase feldspar famous for labradorescence, a dramatic flash of iridescent blue, green, and gold across a dark gray stone.

Translucent banded calcium-carbonate stone deposited in caves and springs, prized for ornamental carvings despite its softness.

A creamy pink-and-white chalcedony from Madagascar containing flower-like plume inclusions that resemble blossoms suspended in stone.

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