Introduction to Mineralogy Dr. 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/cm 3, Kg/m 3 derived, intrinsic 2)Specific Gravity: δ mineral / δ water = dimensionless, relative 3)Streak: color of powdered compound (scattering>reflection) e.g. all SULPHUR streaks Yellow

Jolly Balance for Specific Gravity G = W AIR / (W AIR – W H2O ) Dry pan Wet pan Calibrated Spring Leveling Feet

Same Structure - Different Cation

Density depends on Composition 28.5 at.% Fe100 at. % Fe

Physical Properties that depend on External Force & Internal Strength 4) 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 under standard applied force Scratch resistance of a fresh Mineral surface

TENACITY resistance to deformation

Partings (irregular, discontinuous, infrequent) Basal – Pyroxene 8 sided prisms Rhombohedral – Corundum Hexagonal prisms

Cleavage directions & forms Octahedral 109.5° 4 pinacoids, (111) Cubic 90° 3 pinacoids, (100) Dodecahedral 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, greasy 2)Smell: earthy, sulphurous, heat dependance 3)Taste: metallic, salty, bitter 4)Solubility: in water, acid, base, oil 5)Magnetism: induction remnant, ferro, para, dia 6)Radioactivity: α, β, γ & energies 7)Conductivity: electric current, heat 8)Piezoelectricity: pressure induced polarization 9)Pyroelectricity: heat induced polarization

Quartz Piezoelectric LCD Watch