Mineral - A naturally occurring, inorganic, homogeneous solid with a definite chemical composition and an ordered atomic arrangement. naturally occurring - materials synthesized in laboratory do not count, must be formed by natural processes in wild inorganic - not formed by organic chemistry (e.g., sugars, etc.) homogeneous solid - single substance in solid phase which cannot be physically separated into simpler compounds definite chemical composition - composition can be represented as chemical formula (e.g., NaCl), although variation in exact composition is possible (e.g., (Mg, Fe)2SiO4 ) [range in color, hardness, specific gravity] ordered atomic arrangement – repeating structure at the atomic level, which expresses as symmetry in large specimens, i.e., crystalline structure. http://www.uoregon.edu/~jrice/geol311
COLOR Quartz SiO2 Hardness = 7 Rose Quartz Smokey Citrine Amethyst Carnelian Onyx Jasper
CRYSTAL FORM Figure 3.4
Good for metallic and opaque minerals, softer than the streakplate Figure 3.7 Good for metallic and opaque minerals, softer than the streakplate
HARDNESS Figure 3.9
HARDNESS Figure 3.8
metallic Luster - quality of light reflected from mineral surface pyrite metallic silver gold
non-metallic vitreous (glassy) pearly resinous Luster quality of light reflected from mineral surface non-metallic Some minerals may be listed in both metallic and non-metallic, or in the incorrect table, i.e., limonite vitreous (glassy) pearly resinous
CLEAVAGE Cleavage: Breaks along planes of weakness See the way light reflects back at you (I cannot see this for you). Rotate the mineral to “find” reflective surfaces. When you find a cleavage plane, rotate Figure 3.10
CLEAVAGE Figure 3.10a
CLEAVAGE Figure 3.10b
CLEAVAGE Figure 3.10c
CLEAVAGE Figure 3.10d
Figure 3.12
NO CLEAVAGE - FRACTURE Figure 3.12a
CLEAVAGE – 1 PLANE, EXCELLENT Figure 3.12b
Figure 3.13
CLEAVAGE – 2 PLANES, GOOD Figure 3.12c
Figure 3.15
Figure 3.12d
Figure 3.14
Figure 3.14a
Figure 3.14b
CLEAVAGE – 3 PLANES, GOOD Figure 3.12e
CLEAVAGE – 3 PLANES, GOOD Figure 3.12f
CLEAVAGE – 4 PLANES, GOOD Figure 3.12g
CLEAVAGE – 6 PLANES, GOOD Figure 3.12h
EFFERVESCENCE Minerals like calcite react with weak acid, dissolving the mineral and producing lots of bubbles (effervescence) Calcite: CaCO3 HCl + CaCO3 > H2O + Cl- + Ca+ + CO2 Dolomite: CaMg(CO3)2
SPECIFIC GRAVITY Mass / Volume (gm/cm3) Orthorhombic Carbonates All minerals have same structure, only cation differs Mineral Formula Cation g/cm3 Aragonite CaCO3 20 2.95 Strontianite SrCO3 38 3.76 Witherite BaCO3 56 4.29 Cerrusite PbCO3 82 6.55 Figure 3.17
PAGE 90 Figure 3.18
PAGE 91 Figure 3.18
PAGE 93 Figure 3.21a
UnFigure Pg101_1
ONE QUARTZ CRYSTAL, DOUBLY TERMINATED UnFigure Pg101_1b
MULTIPLE CRYSTALS: Galena, Flourite UnFigure Pg101_1c
Look at minerals: Galena, Olivine IGNEOUS ROCK, Granite, with quartz, potassium feldspar, plagioclase, biotite Randomly Oriented. Look at minerals: Galena, Olivine UnFigure Pg101_1d