Graphite is a crystalline (organized)
form of the element Carbon
and it occurs naturally. It is often
found in both metamorphic and
igneous rocks around the world.
It is a very soft, lightweight
mineral and attaches to other
materials very easily. It is also
very heat-resistant, making
it very versatile. Graphite is
commonly used in pencils.
Scoria is an igneous rock
with many round, bubble-like
cavities. These cavities form
when magma with lots of gas
inside flows from a volcano.
As the lava emerges, the gas
begins to escape from the rock
and the bubbles form. As a
result, scoria is often lightweight.
Scoria is usually black, gray, or
sometimes even reddish brown.
Limestone is a sedimentary
rock and is composed mainly
of calcium carbonate as the
mineral calcite. Limestone
usually forms in calm, shallow
water from the accumulation of
shell, coral, and algae. Because
of this, limestone is often found in
tropical locations with abundant
reef life and activity. Chalk is a
variety of limestone.
Selenite is a variety of gypsum
and is characterized by a clear
appearance. Gypsum is a soft
mineral and is most often found
in sedimentary deposits.
Graphite
Scoria
Limestone
Selenite
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