Introduction to MineralogyDr. Tark Hamilton

Chapter 2: Lecture 6

Camosun College GEOS 250

Lectures: 9:30-10:20 M T Th F300

Lab: 9:30-12:20 W F300

Mineral Physical Properties(non-optical)

1) Mass/Volume: Density, Specific Gravity

2) Strength: Hardness, Tenacity, Parting, Fracture, Cleavage

3) Chemical Physical: Feel, Smell, Taste, Solubility, Streak, Magnetism, Radioactivity, Conductivity, Piezoelectricity, Pyroelectricity

Physical Props Definitions

1) Density: Mass/Volume, g/cm3 , Kg/m3 derived, intrinsic

2) Specific Gravity: δmineral / δwater= dimensionless, relative

3) Streak: color of powdered compound (scattering>reflection) e.g. all SULPHUR streaks Yellow

Jolly Balance for Specific Gravity

G = WAIR / (WAIR – WH2O )

Dry pan

Wet pan

Calibrated Spring

Leveling Feet

Same Structure - Different Cation

Density depends on Composition

28.5 at.% Fe 100 at. % Fe

Physical Properties that depend on External Force

& Internal Strength4) Hardness: scratch test & various others

5) Tenacity: resistance to breakage, deformation

6) Fracture: equidimensional breakage patterns

7) Parting: oriented, irregular discontinuities

8) Cleavage: planes of weak or infrequent bonds

MOH’S HARDNESS SCALE

Relative versus Absolute Hardness

Deformation understandard applied force

Scratch resistance of a freshMineral surface

TENACITYresistance to deformation

Partings(irregular, discontinuous, infrequent)

Basal – Pyroxene8 sided prisms

Rhombohedral – CorundumHexagonal prisms

Cleavage directions & formsOctahedral 4 @ 109.5°

4 pinacoids, (111)Cubic 3 @ 90°

3 pinacoids, (100)Dodecahedral 6 @ 116.6°

6 pinacoids, (110)

Prismatic 2 = (2 dihedral angle)Basal 1(Pedion)

Why not pinacoidal, ?Rhombohedral 3

No 90° or 60°/120°

Chemical & Physical Properties

1) Feel: surface texture, slippery, soft, greasy2) Smell: earthy, sulphurous, heat dependance3) Taste: metallic, salty, bitter4) Solubility: in water, acid, base, oil 5) Magnetism: induction remnant, ferro, para, dia6) Radioactivity: α, β, γ & energies 7) Conductivity: electric current, heat8) Piezoelectricity: pressure induced

polarization 9) Pyroelectricity: heat induced polarization

Quartz Piezoelectric LCD Watch