N. Lindsley-Griffin, 1999
Quartz
• Even when the crystals are different sizes, angles between equivalent faces are the same
• For different minerals, angles are different.
3 3
1 12 2
4 4
Crystal Interfacial AnglesCrystal Interfacial Angles
N.Lindsley-Griffin, 1999
HabitHabitHabit - distinctive shape of the way the mineralcommonly (habitually) appears
Concentric shells -- malachite
Fracture describes how a mineral breaks on an irregular surface rather
than along cleavage planes
N. Lindsley-Griffin, 1998
Types of fracture: Smooth Rough Splintery Conchoidal
© Houghton Mifflin 1998; Lindsley 2000
HardnessHardness
Mohs hardness scale: 1 = softest mineral; 10 = hardest
Diamond 10Corundum 9Topaz 8Quartz 7Feldspar 6 Steel file (6.5)Apatite 5 Glass (5.5- 6)Fluorite 4Calcite 3 Copper penny (3.0)Gypsum 2 Fingernail (2.5)Talc 1
Hardness -- the resistance to being scratchedMohs scale measures relative hardness, the ability of one mineral to scratch another
The 10 minerals of Mohs relative hardness scale
1 Talc 2 Gypsum
3 Calcite 4 Fluorite 5 Apatite
6 Feldspar7 Quartz
8 Topaz
9 Corundum 10 Diamond
N. Lindsley-Griffin, 1999
© Houghton Mifflin; N. Lindsley-Griffin, 1998.
LusterLuster
Luster - the appearance of a mineral in reflected light
Types of luster: Metallic Nonmetallic Pearly Vitreous Resinous Silky Dull Earthy
Metallic luster ofpyrite
Earthy luster oflimonite
Metallic Luster is characteristic of ore minerals and others that contain metal cations.
N. Lindsley-Griffin, 1998