Photo of Plasma Chalcedony in Processed & Rough Form
Plasma Chalcedony is a mineral with a hardness of 7 out of 10 on the Mohs scale of mineral hardness [?]. These Trigonally structured gems are made of silicon dioxide, their full chemical compound being SiO2.
Plasma is a massive, semitransparent, leek to dark green variety of Chalcedony (a microcrystalline variety of the Quartz group), microgranular or microfibrous, consisting of speckles of red or brownish-red jasper, resembling drops of blood.
It is translucent to opaque, may be dark green to bright-green, apple-green, or nearly emerald-green, containing microfibrous of actinolite, frequently flecked with white or yellowish spots. Those with red spots are known as bloodstone. Particles of various silicate minerals (chiefly of the chlorite group) disseminated through which may be varied by the presence of white or yellowish patches. Its green color caused by chlorite. The colors are not always constant.
Plasma is also called heliotrope (its old name) and bloodstone jasper.
Brazil, Australia, India, Madagascar, Egypt, South Africa, the northwestern states of the USA, have commercial deposits of plasma.
The names heliotrope, now hardly used, and bloodstone, still in common use, are used for a type of chalcedony or plasma with spots of iron oxide or red jasper resembling blood spots against a dark green background. Good-quality material comes from the Deccan trap-rocks, India, from Brazil and many other countries.
The specific gravity [?] for Plasma Chalcedony is 2.61, its refractive index [?] is 1.53-1.54, and its double refraction [?] is 0.004.
History
During the Middle Ages, special magic powers were ascribed to plasma with red spots, as the spots were thought to be drops of Christ's blood.
Industrial Usages
Plasma is often used in signet rings, carved objects and amulets.
It has been used in imitation of jade, along with several varieties of quartz which include other green varieties of chalcedony, chrysoprase and also green aventurine quartz (otherwise known as Indian jade), which is coloured by inclusions of the chromian muscovite mica, fuchsite.
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Bloodstone: Bloodstone is a member of the Chalcedony group. Why is it called Bloodstone? Well because in polished and rough form this gem / mineral looks like blood, on a stone. (see photo) Bloodstone is sometimes referred to as Plasma or Heliotrope. Heliotrope is a birthstone for March. The name plasma is used to define a bloodstone with yellow inclusions, and not red ones.Despite its relative hardness (7 o (read full)
Chrysoprase: Chrysoprase is a massive, translucent, dull leek-green to yellow-green compact quartz aggregate, a variety of chalcedony. It is a crystalline quartz leek-green in color containing swarm of green hair-like fibers amphibole actinolite, which is responsible for green color. Its color is caused by fibrous ferrohornblende aggregates or disseminated chlorite minerals. The stone is more translucent than (read full)
Nephrite: Nephrite is a silicate of calcium, magnesium, and iron, containing fluorine and hydroxyl. It is an amphibole of the actinolite series. It occurs in all colors, also striped and spotted, but the most valuable color is green. The amphiboles of the tremolite-actinolite series usually occur as elongated, parallel, radiating, or even fibrous crystals; but the variety known as nephrite has a very compa (read full)
