PENGETAHUAN ASAS GEOLOGI : BASIC MINERALOGY

EARTH MATERIALS

Mineral: definition

1.         Solid
2.       Crystalline
3.       Inorganic
4.       Naturally occurring material
5.       Fixed range of chemical composition ( e.g plagioclase : feldspar)
6.       Fixed chemical composition
7.       Ordered atomic arrangement

      Classification Based on :

Structural aspect

Compositional aspect (anion complex :e.g –(PO4,-CO3, OH)

     Standardization (nomenclature) : 

 Class-----subclass
(silicates, oxides,hydroxides,carbonates,phosphate, sulphate,sulphides,halides, native elements)

Group ----subgroup
[ amphiboles(hornblende), plagioclase(albite, anorthite,orthoclase,microcline :feldspar) ]

Subclasses : silicates

Nesosilicates (GAKOSTS)

Garnet, andalusite,kyanite,olivine,staurolite,topas,silimanite

Sorosilicates,

Epidote,lawsonite

Inosilicates,

Single chain : pyroxene(augite) and diopside

Double chains: hornblende

Cyclosilicates,

Beryl, tourmaline

Phylosilicates, (BSMC)

Talc,biotite,serpentin,muscovite,chlorite

Tectosilicates (QPM)

Quarts,plagioclase, microcline

Other classes :

Oxides : hematite,magnetite,ilmenite,corundum,cassiterite

Hydroxide : bauxite,goethite

Carbonates : (cams) calcite,aragonite,malachite,siderite

Phosphate : apatite

Sulphate : barite,gypsum

Sulphide(bling2) : galena,pyrtite,sphalerite

Halides : halit,fluorite

Native elements : sulphur, graphite

PHYSICAL CHARACTERISTIC OF MINERALS :

1. .     Colour
2. .      Luster : appearance of mineral surf. In reflected light
3. .      Streak : finely powdered mineral
4. .      Cleavage : tendency of  mineral to break parallel (VdW)
5. .      Fracture : direction of breaking(flat/unflat)
6. .      Hardness
7. .      System
8. .   Habit 

Crystal systems: 6 basic crystal system

      1.      Cubic                                                                                                     

      2.      Tetragonal                                                                                              

      3.      Orthorhombic

      4.      monoclinic

      5.      triclinic

      6.      hexagonal/trigonal

Crystal Habit :

Single mineral :

Cubic, prismatic, bladed, acicular, capillary/filiform

Aggregates/group of crystal :

      1.      Massive : barite,pyrite,ilmenite,malachite,

      2.      Lamellar : BSMC

      3.      Botryoidal : hematite, malachite

      4.      Concretion : geothite

      5.      Fibrous : serpentine

      6.      Columnar/euhedral : beryl,apatite,corundum,aragonite

      7.      Reniform : sulphur

      8.      Granular : olivine

      9.      Prismatic : barite,sphalerite

Luster :

Metallic :pyrite,galena, hematite,ilmenite

Submetallic : magnetite

Resinous :sulphur,sphalerite

Adamantine : cassiterite

Greasy/Silky : gypsum, talc,graphite

Mohs scale : (1-10)

Talc,gypsum,calcite,fluorite,apatite,orthoclase,quarts,topas,corundum,diamond

Crystallography :

Diad (2-fold) -2 faces, 2 times similar faces found—triad---tetrad---hexad

Parallel planes : CENTER

PLANES OF SYMMETRY : CUT INTO MIRROR IMAGE