Chalcedony is cryptocrystalline quartz, formed at low temperatures in volcanic cavities, the crystals are so tiny that en mass they appear more like porcelain.
Chalcedony is a form of chert and was known and used by prehistoric man, for weaponry, tools and decoration.
Fortification agate resembles the the ariel view of an ancient hill fort.
Agate is mainly found in basalt geodes of rock, distinctive bands are formed when basalt lava solidifies quickly trapping bubbles within the stone, as the lava cools silicate minerals escape into these bubbles and form a gel, (a little like opal); as the iron and maganesium compounds from the surrounding rock are absorbed into the gel-like bubbles they form iron/magnesium hydroxide which hardens and forms the signatory bands of agate.
Fancy Jasper aka
Indian Agate.
Sometimes jasper can replace the organic matter - as in 'petrified wood'.
A comparatively recent 'discovery' from Australia.
This stone appears to have the same characteristics as the crypto-crystalline chalcedony, a personal favourite in a range of "hot" colours, brick red, lilac, mustard, coffee and cream.
