How Does Turquoise Form?How Does Turquoise Form?

Turquoise Specialist Mini Course

How Does Turquoise Form?

turquoises - nuggets and cabochons
Turquoise nuggets and cabochons. Photo © Joel E. Arem, PhD, FGA. Used with permission.

What is Turquoise?

Unlike popular transparent gemstones like diamond and aquamarine, gem-quality turquoise doesn’t form as a single solid crystal. Instead, turquoise is a porous mineral aggregate known as a cryptocrystalline rock, comprised of many tiny individual micro-crystals. Chemically, turquoise is a hydrated copper and aluminum phosphate with the formula CuAl6(PO4)4 (OH)8 · 5H2O. Depending on the growth environment, its chemical structure may also contain iron, zinc, and other impurities.

how does turquoise form - crystals on matrix
Only one source produces turquoise in crystalline form: Lynch Station, Virginia, USA. However, the individual turquoise crystals on this quartz matrix measure less than 1 mm across, too small for gem use. Matrix 7.3 x 6.0 x 2.3 cm. © Rob Lavinsky, Used with permission.

Turquoises form via a sedimentary process at the Earth’s surface. Scientists classify turquoise as a secondary mineral since it consists of transformed primary materials cemented into solid stone. In contrast, gemstones like diamond and aquamarine require immense heat and pressure deep in the Earth to crystallize.

Where Do Turquoises Form?

First and foremost a desert gem, turquoise requires a relatively

Emily Frontiere

Emily Frontiere is a GIA Graduate Gemologist. She is particularly experienced working with estate/antique jewelry.

International Gem Society

Never Stop Learning

When you join the IGS community, you get trusted diamond & gemstone information when you need it.

Become a Member

Get Gemology Insights

Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!