GLG 101 Quiz: STUDY FOR GEOLOGY TEST Chapter 3-2
Document Summary
This test compares the resistance of a mineral to being scratched by ten reference minerals known as the mohs hardness scale. Talc 1, gypsum 2, calcite 3, fluorite 4, apatite 5, orthoclase 6, quartz 7, topaz 8, corundum 9. Cleavage: a mineral that regularly breaks along a predetermined plane has cleavage. Cleavage planes can be repeated, crystal faces are a single surface. Cleavage surfaces arise due to planes of weak bonding within the crystal and can be seen because of crystal breakage (or near breakage). Crystal faces are solitary, occurring only at the surface of the crystal. Crystal faces are formed by the growth of the crystal. The tetrahedra in the silicate sheets group share three oxygen atoms and therefore link to form two-dimensional sheets. Because of their structure, sheet silicates have cleavage in one direction and they occur in books of very thin sheets. (in micas, each silicon-oxygen tetrahedron shares three oxygen atoms with adjacent, coplanar tetrahedra.
