Some science behind the scenes

Quartz

Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar.

Quartz is a naturally occurring electret.

Electret (formed of elektr- from "electricity" and -et from "magnet") is the electrostatic equivalent of a permanent magnet. Waxes, polymers and resins are all electrets.  Natural polymeric materials include shellac, amber, natural rubber and cellulose, which as we have seen is the main constituent of wood [and paper]. Excess charge within an electret decays exponentially. So to put this very simply any charge generated in stones with quartz crystal in them will be held and builds up. 

Quartz may well be behaving like a form of silicon chip where whatever happens at the time is ‘imprinted’ on the quartz crystals ready for a sensitive person to unlock the imprisoned records.

Standing stones have a memory!! So may many other forms of stones with quartz in them including buildings built with stone for example granite.

There are many different varieties of quartz, several of which are semi-precious gemstones.  Pure quartz, traditionally called rock crystal (sometimes called clear quartz), is colorless and transparent (clear) or translucent. Common coloured varieties include

  • Citrine - is a variety of quartz whose colour ranges from a pale yellow to brown. Natural citrines are rare. It is nearly impossible to tell cut citrine from yellow topaz visibly, but they differ in hardness
  • Rose quartz - is a pale pink to rose red hue. The colour is usually due to trace amounts of titanium, iron, or manganese. In crystal form (rarely found) it is called pink quartz and its colour is thought to be caused by trace amounts of phosphate or aluminium. The colour in crystals is photosensitive and subject to fading.
  • Amethyst - ranges from a bright to dark or dull purple color
  • smoky quartz - is a gray, translucent version of quartz. It ranges in clarity from almost complete transparency to a brownish-gray crystal that is almost opaque. Some can also be black
  • milky quartz - may be the most common variety of crystalline quartz and can be found almost anywhere. The white color may be caused by minute fluid inclusions of gas, liquid, or both, trapped during the crystal formation.
  • Prasiolite – mint green and transparent.

 

 

 

 

 

Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are

Chalcedony

Cryptocrystalline quartz and moganite mixture. The term is generally only used for white or lightly coloured material. Otherwise more specific names are used.

Agate

Multi-coloured, banded chalcedony, semi-translucent to translucent

Onyx

Agate where the bands are straight, parallel and consistent in size.

Jasper

Opaque cryptocrystalline quartz, typically red to brown

Aventurine

Translucent chalcedony with small inclusions (usually mica) that shimmer.

Tiger's Eye

Fibrous gold to red-brown coloured quartz,

Rutilated quartz

Contains acicular (needles) inclusions of rutile

Carnelian

Reddish orange chalcedony, translucent

Sard and carnelain

Carnelian is a brownish-red mineral which is commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder and darker. The difference is not rigidly defined, and the two names are often used interchangeably. Both carnelian and sard are varieties of the silica mineral chalcedony colored by impurities of iron oxide.

Dumortierite quartz

Contains large amounts of dumortierite crystals

Heliotrope or ‘bloodstone’

Heliotrope is a form of chalcedony (which is a cryptocrystalline mixture of quartz and its monoclinic polymorph moganite). The "classic" bloodstone is green chalcedony with red inclusions of iron oxide or red jasper. Sometimes the inclusions are yellow, in which case the mineral is given the name plasma.  The red inclusions are supposed to resemble spots of blood; hence the name "bloodstone". The name "heliotrope" (from Greek ήλιος helios, Sun, τρέπειν trepein, to turn) derives from ancient observations about the manner in which the mineral reflects light. These are described, by  - for example - Pliny the Elder (Nat. Hist  37.165).  Heliotrope features in one of Boccaccio's stories in the Decameron

Man-made crystals

 Man-made quartz crystals include

  • Gallium orthophosphate (GaPO4), a quartz analogic crystal
  • Langasite (La3Ga5SiO14), a quartz analogic crystal

 

Observations

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