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Often used as the first step in the creation of beautiful gemstones, cleavage is the tendency of crystalline minerals to fracture along structural planes. These planes of comparative weakness are a result of the regular arrangement of atoms in the crystal, which create repeating surfaces that are apparent when the mineral is subjected to forces such as a sharp impact. Calcite, while not as exciting as a diamond, has the unique trait of having perfect cleavage planes in 3 directions, forming rhombehedrons.
Cleaving your Calcite sample is actually quite simple.
But first a note on safety:
BE SURE TO USE EYE PROTECTION AT ALL TIMES. When the calcite shatters, small fragments can be thrown out in random directions. All participants in the experiment should wear eye protection at all times in order to prevent injury.
Once eye protection is in place, place the calcite sample on a solid surface. You might want to use one layer of towel to keep it from sliding around.
Place the tapered end of the chisel perpendicular to the surface of the calcite, and tap the flat end of the chisel sharply with a hammer.
The calcite will shatter into 2 or more pieces, all keeping the same general shape as the original
sample. While the proportions may change, the overall shape will remain the same. There will usually be some small amount debris (dust/grit) as well.
If you repeat the process with one of the smaller pieces you have just created, the resulting pieces
will again retain the same shape as the original sample.
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