Septarian cabochon

Septarian cabochon

Size: approx. 22x18mm

Weight: 16.80ct

Dark brown with black and grey.

Septarian started their life as a ball of mud… During the Cretaceous period these ancient mud balls dried and cracked before mineralisation occurred.  For those who like a little more detail, calcite leeched into the cracks forming calcite crystals on a layer of aragonite.  The bentonite clay surrounding this was eventually replaced with limestone turning the ball of mud to stone.  They are found in Madagascar and Utah, USA.

With a hardness of 3.5-4, it is best suited to pendants, earrings and brooches with care being needed in rings, bracelets and cufflinks.

Hardness – resistance to scratching and wear

Stability – resistance to alteration by light, heat or chemicals

Toughness – resistance to fracture, cleavage or cracking

Please note you will receive the stone in the photograph