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 Definitions Of Glass
Glass that is formed by volcanic action is called obsidian and can be
found in many parts of the world. Obsidian is formed when the intense
heat of a volcano fuses masses of silica together, forming the hard
glass. Because of natural impurities, it is usually shiny, black, and
opaque, but it can also be very dark red or green; its splinters are often
transparent or translucent. Obsidian can be chipped and flaked to make
arrow and spearheads, knives, and razors. Humans probably began to use
this natural material to make tools as early as 75,000 B.C. As millennia
passed, obsidian became valued for ornamental and ceremonial purposes.
Although other objects were produced, it was usually fashioned into
tools and weapons. It was highly valued and locations of sources were
often closely guarded secrets. Ancient Egyptians imported obsidian from the
region we call Turkey and perhaps even from what we call Iran.
Tektites are rounded, indefinitely shaped glassy objects thought to be
a result of meteoritic impact on either the earth or the moon. Tektites
are found in Czechoslovakia, Indonesia, Viet Nam, Australia, the United
States, etc.
Libyan Desert Glass is found in the Sahara Desert in large sand dunes.
The slightly yellowish lumps were probably created by meteoritic
impact.
Lightning can create glassy formations when it strikes a sandy area
with the right combination of minerals. The resulting crude, brittle,
slender tubes are called fulgurites.
Just as some animals ingest calcium to form their skeletons, some
microscopic sea animals such as diatoms ingest dissolved silica from
seawater to form their skeletons. Huge deposits of the countless skeletons of
these animals account for the mining of diatomaceous earth.
Three Classical States of Matter
Gaseous state: individual molecules separated from one another by
relatively great distances and moving in a chaotic fashion. No interaction
between molecules except for collisions with one another.
Liquid state: molecules are held close by attractive forces, but are
held rigidly in position. They move about changing from one disordered
state to another.
Crystalline state: strong attractive forces hold molecules rigidly in
position. Each molecule occupies a definite position, in a perfectly
ordered three-dimensional lattice.
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