Natural Prehnite

Natural Prehnite

Prehnite is a calcium aluminum silicate (Ca2Al(AlSi3O10)(OH)2), usually translucent, in soft shades of green to yellow-green. It often forms rounded, grape-like masses rather than single crystals, and many pieces carry fine dark needles growing through the stone. With a Mohs hardness of 6 to 6.5 it takes a good polish and suits cabochons and beads.

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Gemstone guide

Natural Prehnite

About prehnite

Prehnite was named in the late eighteenth century after Hendrik von Prehn, a Dutch military officer who brought samples from the Cape of Good Hope. It usually forms in cavities in volcanic rock, often together with zeolites, and its soft, glowing green historically led to it being confused with jade. Good material comes from Australia, Mali, South Africa and China. Prehnite is rarely treated.

What you'll find in this collection

Our prehnite comes from Africa and is untreated. You'll find large oval and pear cabochons from about 35 to over 85 carats, many with dark needle inclusions of epidote or tourmaline crossing the pale green.

How to recognise prehnite

Prehnite has a soft, almost glowing translucency and a pale green to yellow-green color that is fairly even across the stone. The dark needles seen in many African cabochons are a natural inclusion and a good sign of genuine material. It is harder than serpentine and lighter in color than most jade.

Caring for prehnite

Clean prehnite with warm soapy water and a soft brush, and avoid ultrasonic and steam cleaners, acids and sudden temperature changes.

Every stone is natural, and each listing gives its weight, size, origin and treatment, with photos of the actual stone.