The Cryptocrystalline Chalcedony

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This stunning black and white Chalcedony quartz agate is quite mesmerizing. This one is from Southeast Region, Brazil. The rear end is terminated quartz which makes it a crystal and agate in one specimen. This particular find can be cut into at least 8 amazing slabs.

Chalcedony quartz is by far one of the most significant materials around. This special type of quartz is popular with the jewel lovers and has many scientific and industrial uses as well.

The name ‘chalcedony’ is thought to be taken from ‘Chalcedon’, which was an ancient seaport of present day Turkey.

The term, ‘chalcedony’, is mostly used in reference to a specific gemstone species called cryptocrystalline quartz. Technically it is often referred to as ‘actual chalcedony’ or ‘chalcedony in the narrow sense’.

Helping to minimize the confusion ‘carnelian’, ‘jasper’ and ‘banded agate’ are traded by their name. This stone is  ‘chalcedony’ is distinguished by translucency and its solid, lighter color, typically ranging from bluish to white or gray.

It was recently found to be a combination of quartz and another silicate mineral; moganite, and it forms with a hexagonal crystal structure.

Chalcedony loves a good polish.  An amazing aspect of this cool mineral is that some varieties exhibit an inner glow after a prolonged polish!


photo credit: Rob Lavinsky,

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