The Technical Scientific Stuff
Technical stuff About rocks and crystals is not my strong suit. I'm just going to skim over a lot of that .
Our main focus here is on the mystical and healing side of crystals but
most of us would like know a little bit about the more concrete side as
well sometimes knowing about the origins of a kind of stone can give us
guidance in working with it .
Rocks can be placed in three groups for convenience :
Include Granite ,rhyolite, obsidian, and basalt They are formed by
the solidification of molten magma that emerges via volcanic activity
and emerges or erupts through vents or fissures in the Earth's Crust
The nature and properties of these crystals vary greatly depending in
part on the conditions under which the magma solidified . fast cooling
creates rocks that tend not to have crystals slower cooling can give
similar kinds of atoms trapped in the magma time to find each other and
form crystals . There are thousands of different kinds of igneous
such as limestone , sandstone, shales, halites coals, and gypsum
are formed by the accumulation of "sediments" these are fine rock
particles or fragments, skeletons of microscopic organisms, or minerals
leached from rocks that have accumulated from weathering. These
sediments have been redeposited under water and were later compressed
in layers over time and are classed as either evaporative (often water
soluble ) or organic sedimentary rocks.
such as marble, slate , schist, gneiss and quartzite are formed by
the alteration of igneous and sedimentary rocks through heat and/or
pressure . These physical and/or chemical changes to rocks maybe
exemplified by the formation of marble from thermal changes that have
occurred to limestone.
What is the difference between a rock and a mineral?
A mineral is defined as a substance that must have all four of these
characteristics: It must be found in nature. It must not be made of
anything that has ever been alive (organic). It has the same chemical
makeup wherever it is found and its atoms are arranged in regular
patterns and form crystals. It is solid.
Rocks are sometimes defined as an aggregate or combination of one
or more minerals and the definition is extended to cover clay ,loose
sand and certain limestones.
a crystal is a uniform body with a geometric lattice. the varying
structures of the lattice are the causes of the varying physical
properties of the crystals and therefore also of the minerals and gems.
One way gemstones are classified is by hardness, both scratch
hardness and cutting resistance while the Mohs scale of hardness
developed by Frederich Mohs (1773-1839) is made somewhat obsolete by
modern technology an idea of the general hardness of a stone and
whether it is brittle helps you to protect your stones from damage and
can help with identification from softest to hardest the Mohs scale
Piezoelectricity is that quality by which electricity and sometimes
light is produced by compression . Many cultures and spiritual
traditions have used crystals in ritual, often striking them to produce
flashes of visible light.
Pyroelectricity is that quality of an electrified state or
polarity which is produced by variation in temperature. Quartz has both
piezoelectric and pyroelectric properties which means that the polarity
of quartz crystal will change when subject to pressure or heat as well
as when held.
Shining lines that cross one another like rays from a star, caused by
light reflected by a series of microscopic canals.
Bands of light and dark that vary in width and hue as the stone is turned in the light.
A mineral's tendency to split when force is applied, leaving a flat
surface. This happens when there are layers of weakness within the crystal.
Composed not of a single crystal crystal but of many extremely small
crystals, fused together.
The way different colors or shades can be seen according to the angle
at which you look at the crystal.
Light is split into two rays, producing a double image.
Any embedded foreign body, such as rutile crystals in Quartz, or an ant in Amber.
The colorful play of refracted light reflected from cleavage planes.
Refracted light is bent so as to enlarge, reduce, invert, or otherwise distort an image.
( Some of this is adapted from "The Handy Science Answer Book " and from
package notes from several little rock collection kits and Gemstones of
the world by Walter Schumann)
Solarraven ~ Peggy Jentoft