Just as wood is easier to split with the grain than against it, gemstone cleavage is the tendency of certain crystals to break along definite plane surfaces. If there are planes in a crystal structure with relatively weak atomic bonds, the crystal is more likely to break along those planes.
What is perfect cleavage in gemstones?
Minerals with perfect cleavage will cleave without leaving any rough surfaces; a full, smooth plane is formed where the crystal broke. Minerals with good cleavage also leave smooth surfaces, but often leave over minor residual rough surfaces.
How do you describe mineral cleavage?
Definitions. Cleavage – The tendency of a mineral to break along flat planar surfaces as determined by the structure of its crystal lattice. These two-dimensional surfaces are known as cleavage planes and are caused by the alignment of weaker bonds between atoms in the crystal lattice.
How do you cleave crystals?
The procedure is to place the blade parallel to one of the existing edges, and then tap lightly with the small hammer. Cleaving occurs instantly and the only time there is a problem is when the razor blade being used gets dull (it should be changed after every several cleavings).
How do you identify cleavage?
To determine the angle of cleavage, look at the intersection of cleavage planes. Commonly, cleavage planes will intersect at 60°, 90° (right angles), or 120°. Be cautious when you see a flat surface on a mineral – not every flat surface is a cleavage plane.
What is quartz cleavage?
Quartz has no cleavage.
What is cleavage in biology?
In developmental biology, cleavage is the division of cells in the early embryo. … The different cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula.
What is cleavage vs fracture?
Cleavage is the property of a mineral that allows it to break smoothly along specific internal planes (called cleavage planes) when the mineral is struck sharply with a hammer. Fracture is the property of a mineral breaking in a more or less random pattern with no smooth planar surfaces.