2. What is a mineral?
►The building block of rocks
Naturally occurring (versus synthetic)
Inorganic (no C-H bonds)
Crystalline solid (ordered internal structure)
Has a definite but not fixed chemical
composition
6. Chemical composition
of minerals
►8 elements make up 98% of Earth’s crust
Oxygen
Silicon
Aluminum
Iron
Calcium
Magnesium
Potasium
Sodium
7. Chemical composition
of minerals
►A few elements ARE minerals (eg: gold)
►Most are comprised of 2 to 5 elements
Held together by + / - electrical charges
88 elements form over 3,500 minerals
9 rock-forming mineral groups
8. Chemical Composition
Mineral Formulas
►Quartz – SiO2 Silicon and Oxygen
►Calcite – CaCO3 (Calcium and Carbon and
Oxygen)
►Olivine – (Fe,Mg)2SiO3 (Iron, Magnesium,
Silicon and Oxygen)
►Potassium Feldspar – KAlSi3O8 (Potassium,
Aluminum, Silicon, and Oxygen)
11. Crystals
►Crystal – any substance whose atoms are
arranged in a periodic, repeating pattern
This pattern is a crystalline structure
Unit cell – the smallest group of atoms making
up the unique pattern
16. Atoms
►The nucleus of the atom contains protons
and neutrons with electrons surrounding the
nucleus.
17. Atomic Particles
►Proton – positive charge
►Electrons – negative charge
►Neutrons – neutral charge
►Atomic number = the number of protons in
the element
►Atomic mass = the number of protons + the
number of neutrons
19. Bonding
►A link between atoms ( by virtue of the
electrons)
►Na (by itself is a metal) plus Cl (by itself is a
poisonous gas)
►But bonded together it makes NaCl – table
salt
► This is Ionic Bonding – one electron is
transferred to the another
24. 2.4 Physical properties of minerals
►Crystal habit
the way crystals aggregate
Prismatic quartz crystals and massive quartz with no crystal shape
25. Physical Properties
►Cleavage
Some minerals tend to break along flat surfaces
due to weak internal bonding
►Fracture
The way a mineral breaks other than cleavage
26. Physical Properties - Cleavage
►One plane – sheets layered together
►Two planes at right angles – stair stepping
►Two planes not at right angles – roof top
►Three planes at right angles
►Three planes not at right angles
27. Physical Properties
►Hardness – Moh’s scale
1 to 10, based on minerals
►Specific gravity
Density relative to water
►Color
Obvious, but limited use
29. 2.4 Physical properties of minerals
►Streak
Color of fine powder
►Luster
The manner it reflects light
►“Other” properties – smell, taste,
magnetism, striations, and reaction to HCl
38. Mineral classes
►Silicates
Most abundant rock-forming minerals
Over 90% of the Earth’s crust contains silicate
minerals
Basic building block for all silicate
minerals – silica tetrahedra
Five groups (Si:O ratio, crystal form)