Crystal form a Crystal: any solid body that grows with planar surfaces. a The interfacial angle in any crystalline structure remains constant
Crystal Form ◼ Crystal: any solid body that grows with planar surfaces. ◼ The interfacial angle in any crystalline structure remains constant
regular Growth of Quartz grains
Iregular Growth of Quartz grains
Fibers of Chrysotile Asbestos
Fibers of Chrysotile Asbestos
Growth Habit and Polymorphism a growth habits The characteristic crystal form of each mineral a Polymorphism: Some elements and compounds form two or more different minerals: C Graphite, Diamond Ca CO3 Calcite, Aragonite Fes rite, Marcasite白铁矿 SiO2 Quartz, Cristobalite方英石
Growth Habit and Polymorphism ◼ Growth habit: ◼ The characteristic crystal form of each mineral. ◼ Polymorphism: ◼ Some elements and compounds form two or more different minerals: ◼ C Graphite, Diamond ◼ CaCO3 Calcite, Aragonite ◼ FeS2 Pyrite, Marcasite 白铁矿 ◼ SiO2 Quartz, Cristobalite 方英石
Cleavage Cleavage is the tendency to break in preferred directions along bright, reflective planar surfaces. aa cleavage surface is a breakage surface, whereas a crystal face is a growth surface The planar directions along which cleavage occurs are governed by the crystal structure. They are planes along which the bonding between atoms is relatively weak
Cleavage ◼ Cleavage is the tendency to break in preferred directions along bright, reflective planar surfaces. ◼ A cleavage surface is a breakage surface, whereas a crystal face is a growth surface. ◼ The planar directions along which cleavage occurs are governed by the crystal structure. ◼ They are planes along which the bonding between atoms is relatively weak