Illustrated · 1 min
Fracture is the distinctive mark revealed when a mineral chips. The difference between cleavage and fracture is that cleavage is breaking on a flat surface, a cleavage plane, and fracture, is the way a mineral breaks on an uneven or curved surface without a particular shape. There are a few different types of fracture:
Conchoidal: A conchoidal fracture leaves behind a round, smooth surface, resembling a semicircular shell. Obsidian has a conchoidal fracture.
Uneven: An uneven fracture leaves behind a rough/irregular surface.
Hackly: A hackly fracture resembles broken metal, with jagged points.
Splintery: A splintery fracture leaves behind long splinters.
Earthy: An earthy fracture leaves behind crumbles of the mineral when it fractures.
Even: An even fracture leaves behind a smooth, straight surface.
Subconchoidal: A subconchoidal fracture leaves behind a smooth surface with irregular rounded corners.
Copper has a hackly fracture
Garnet has an uneven fracture
Galena has a subconchoidal fracture