Module: Rocks and Minerals

crust

outermost solid part of the Earth

rocks

building blocks of the lithosphere

minerals

inorganic elements or compounds with atoms arranged in definite structure

fossils

remains of plants and animals in them

isometric

All three axes are equal in length, and all are perpendicular to one another

Tetragonal

Two of the three axes are equal in length, and all three axes are perpendicular to one another.

orthorhombic

All three axes are unequal in length, and all are perpendicular to one another.

Hexagonal

Of four axes, three are equal length, are separated by equal angles, and lie in the same plane. The fourth axis is perpendicular to the plane of the other three axes. It has lattice points in each of the two six-sided faces.

Triclinic

All three axes are unequal in length, and none is perpendicular to another.

Monoclinic

All three axes are unequal in length, and two axes are perpendicular to each other.

Rhombohedral

All three axes are equal length, and none of the axes is perpendicular to another, but the crystal faces all have the same size and shape.