Rock & Mineral Encyclopedia

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

Turritella Jasper

A fossiliferous jasper packed with spiral snail shells, technically a silicified gastropod limestone from Wyoming.

A brown fossiliferous chalcedony packed with spiral freshwater snail shells, technically agatized fossil rock from Wyoming.

Fossil shells whose original material has been replaced by opal, preserving ancient marine forms in common or precious opal.

Fossil material whose original substance has been replaced by opal, preserving ancient shapes in common or play-of-color opal.