Microcrystalline quartz - Chalcedony
Chalcedony was so named by Agricola (1546) from a stone named after the city of Chalcedon, now called Kadıköy, a district in Istanbul, Turkey.
|Color:||Colorless, white, gray, blue, any color due to embedded minerals|
|Multicolored copy not unusual|
|Hardness:||6½ - 7|
Chalcedony is a non-layered Micro Crystalline variety of Quartz (not to be confused with Blue Lace Agate which is layered)
Chalcedony has different meanings.
Scientific term for Chalcedony Agates to equally large (fibrous) quartz crystals of microscopic and sub-microscopic size.
At least two types can be distinguished based on the striking behavior of thin parts of Chalcedony in polarized light:
- High-speed Chalcedony, with crystallites stacked perpendicular to the c-axis, and the resulting fibers are elongated. The fibers can be rotated around the extension axis.
- Slow Chalcedony or Quartzite, with crystallites stacked parallel to the c-axis, and the resulting fibers are elongated along, as in Macrocrystalline Quartz.
The Chalcedony Group consists of 2 subgroups; the aligned Agate group & the opaque Jasper group and its own Chalcedony group with the following: Chalcedony, Chrysoprase, Flint, Pietersiet.
If in stock you will find below my collection of Raw Gemstones within this group.
Are you looking for cut stones from the Chalcedony Group, then look at CHALCEDOON