Jasper- (from Greek ἴασπις the name means "spotted or speckled stone"), a micro cryptocrystalline rock, consist of mainly of quartz, chalcedony and pigmented impurities of other minerals (epidote, actinolite, clinkstone, mica, brassil, oxides and ferrum oxide and manganese), a semi-precious ornamental stone. The some breeds, which traditionally are classed as Jasper, include feldspar; it is either gray quartzo-feldspathic cherts or acidic effusives (porphyry). Among the breeds of Jasper, you can occur quartz-free, garnet-riched (up to 20% andradite). In ancient times glassy colored (mostly green color) chalcedony was classed as Jasper.
Elemental composition of Jasper is approximately as follows:
SiO2 80—95 %; Al2O3 and Fe2O3 to 15 %; CaO 3—6 %
The variety of Jasper has considerably in texture: massive, spotted, banded, brecciated, puckered and etc. The presence of many nonuniformity impurities provides variety and garishness of colouring. Sole-coloured Jasper is a rarity in nature.
In ancient times, Jasper was used as stamps or amulets to protect from dry period and vision problems. In these latter days Jasper is a popular material for art stone products, cabochons, stone mosaics. When you planishing and polishing require caution: ribbon jasper tends to disintegrate boundary layers. In the era of Catherine the Great Jasper was much sought after, the Queen built stone cutting manufacturers and some large factories for processing Jasper stones.
Depending on the color, pattern, deposit or consistence Jasper can be classified: