Minerals also break in another way. When the break is in a different
direction from that of the cleavage or parting, it is known as the
fracture. A fracture is called _conchoidal_ if the mineral’s broken
surface is curved like the inside of a spoon or shell. Thick pieces of
glass break with this conchoidal fracture. A fracture is described as
_hackly_ if the broken surface has sharp, jagged edges; as _even_, if
the surface is generally flat; and as _uneven_, if it is rough and not
flat. If the mineral breaks into splinters, its fracture is called
_splintery_.
[Illustration: Conchoidal fracture.]