California State Rock & Lithologic Emblem

Serpentine

((Mg, Fe)₃Si₂O₅(OH)₄)

Adopted in 1965

California has a greater number of minerals and a wider variety of rock types than does any other state. Serpentine, a shiny, green and blue rock found throughout California, was named the official State Rock in 1965. It contains the state's principal deposits of chromite, magnesite, and cinnabar. California was the first state to designate a State Rock.

Serpentine is a major rock forming mineral and is found as a constituent in many metamorphic and weather igneous rocks. It often colors many of these rocks to a green color and most rocks that have a green color probably have serpentine in some amount.

Physical Characteristics

• Color is olive green, yellow or golden, brown, or black.
• Luster is greasy, waxy or silky.
• Transparency crystals are translucent and masses are opaque.
• Crystal System is variable, see above.
• Crystal Habits: never in large individual crystals, usually compact masses or fibrous. Veins of viberous serpentine can be found inside of massive serpentine or other rocks.
• Cleavage the varieties of crysotile have none, in lizardite and antigorite it is good in one direction.
• Fracture is conchoidal in antigorite and lizardite and splintery in the crysotiles.
• Hardness is 3 - 4.5
• Specific Gravity is 2.2 - 2.6
• Streak white
• Associated Minerals include chromite, olivine, garnets, calcite, biotite and talc.
• Other Characteristics: serpentine in the rough has a silky feel to the touch and fibers are very flexible.
• Notable Occurances Val Antigorio, Italy; Russia; Rhodesia Switzerland; North Carolina, California, Rhode Island and Arizona, USA and Quebec, Canada.
• Best Field Indicators softness, color, silky feel and luster, asbestos if present and its flexibility