[13th century crosier, a stylized staff used in Christianity, carved from rock crystal (clear quartz).]
The words mineral, rock,
stone, gem, gemstone, and crystal are often used interchangeably but
each has specific meanings.
MINERAL
The
word mineral comes from the Latin minerale
(“obtained by mining”). In geology, a mineral is a naturally
occurring solid substance. Each has a specific chemical composition,
made of either one or more elements, arranged in a regular three
dimensional pattern, producing a crystal structure. Some minerals do not meet all three criteria, lacking a crystal structure, like liquid mercury. They are called mineraloids instead. This category may also includes materials produced by an organic process, like amber, jet, and pearl.
ROCK
AND STONE
Rock
and stone are often used interchangeably in American English but they have
different meanings historically. Both words come from Old English.
Rock meant something large, like a rock formation, and stone meant
something smaller, often transformed by human hands, like a millstone, tombstone, or gemstone. This distinction
still remains in British English.
In geology, a rock is a material made up of two or more minerals. For example, pyrite is a mineral but lapis lazuli is a rock, a combination of golden pyrite, blue lazurite, and white calcite.
In geology, a rock is a material made up of two or more minerals. For example, pyrite is a mineral but lapis lazuli is a rock, a combination of golden pyrite, blue lazurite, and white calcite.
GEM AND
GEMSTONE
The word gemstone comes
from the Old English gimstan, combining the Latin gemma
(“a precious stone, a leaf bud”) and the Old English stan
(“a small rock, a stone shaped for a particular purpose”).
Gemstones are valuable minerals and rocks that are rare, durable, and
have distinctive color or clarity. However, lists of gemstones are
very subjective, changing over time. Organic substances like amber,
coral, and pearl may also be included. Diamond, emerald, ruby, and
sapphire are historically called “precious gemstones” and others,
“semi-precious”. Amethyst was once considered precious until the vast deposits of Brazil lowered its monetary values.
CRYSTAL
The meaning of
crystal has changed over time:
A: Quartz: The word
crystal comes from the Greek krystallos (“ice, frost,
crystal”). The ancient Greeks theorized that quartz was a
petrified form of ice, since it was water clear, cool to the touch,
and resembled an icicle. Its alternative name rock crystal reflects
this etymology.
B: Colorless Glass: From
antiquity to the late 19th century, quartz was a luxury
item, often carved into vessels like pitchers, along with other
semi-precious stones. Because these objects were so expensive, both
labor intensive and wasteful of materials, imitations in glass
developed. During the 15th century, Venetian glass makers
produced an incredibly popular faux quartz called cristallo
(Italian, “crystal glass”).
Since then, high quality colorless glass has also been called crystal.
C:
The Structure of Minerals: During the 17th
and 18th
century, the chemical patterns that produce minerals began to be
studied scientifically. Because the geometric nature of quartz is clearly visible, they were named crystal structures, after it. In geology, a
crystal is a substance with a regular shape, due to the repeating
internal structure of its atoms.
©
2012, C. L. Matthews
[Image Source: Public domain, Wikipedia Commons]
[Image Source: Public domain, Wikipedia Commons]
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