RocksIgneous rocks –
• Formed by the cooling and crystallization of hot molten rock called magma
• Igneous means – formed by fire
• 95% of the earth crust are igneous rocks
• examples include basalt and granite
From yahoo images
Rocks
Sedimentary rocks – • Formed by weatherd
material carried by water, wind or ice.• Most common rock in the upper part
of the earth’s crust• They cover 2/3 of earths surface.• Examples include sandstone, shale
and limestone
From yahoo images
Rocks
Metamorphic rocks –
• Formed from pre-existing rocks that are transformed under high
• temperature and pressure.
• Metamorphic means – changed in form
• Examples include marble, slate and diamond
From yahoo images
Minerals
• Minerals – The building blocks of rocks.
• Minerals are naturally formed, generally inorganic crystalline solid composed of an ordered array of atoms having a specific composition.
• Minerals differ from one another in their combination and proportion of elements and internal arrangement of atoms.
Classifying Minerals
• Polymorph – mineral composed of the same atom but have different crystal structure.
Classifying MineralsMohs Hardness Scale
Hardness is measured on the Mohs Scale, identified numerically hardness of by standard minerals, from 1 (softest) to 10 (hardest):
1. Talc 2. Gypsum 3. Clacite 4. Fluorite 5. Apatite 6. Orthoclase 7. Quartz 8. Topaz 9. Corundum 10.Diamond
• A mineral of a given hardenss will scratch a mineral of a lower number. With a systematic approach, you can use minerals of known hardness to determine the relative hardness of any other mineral.
Classifying Minerals
• Cleavage – tendency of a mineral to break along planes of weakness.
• Fracture – break that is not along the lines of a cleavage plane
From yahoo images
Classifying Minerals
• Luster – appearance of its surface as it reflects light
• Luster is independent of color
From yahoo images
Classifying Luster of Minerals• Adamantine - very gemmy crystals • Dull - just a non-reflective surface of any kind • Earthy - the look of dirt or dried mud • Fibrous - the look of fibers • Greasy - the look of grease • Gumdrop - the look a sucked on hard candy • Metallic - the look of metals • Pearly - the look of a pearl • Pitchy - the look of tar • Resinous - the look of resins such as dried glue or chewing
gum • Silky - the look of silk, similar to fibrous but more compact • Submetallic - a poor metallic luster, opaque but reflecting little
light • Vitreous - the most common luster, it simply means the look of
glass • Waxy - the look of wax
Classifying Minerals
• Color – is usually a poor way to judge minerals – the same mineral may exhibit a variety of colors
• Streak – color or mineral in its powder form. Usually obtained by rubbing across a porcelain plate.
From yahoo images
Classifying Minerals
• Specific Gravity – Density like measurement based on a comparison with the density of water.
From yahoo images
Makeup of Rocks and Minerals
• 118 know elements
• 88 are naturally occurring
• These combine to make 3400 different minerals
• About two dozen minerals are abundant
• These are made from 8 elements
Makeup of Rocks and Minerals
• These 8 elements make up 98 % of the mass of the crust
• Half of this mass is due to O alone
• These minerals are broken into groups – silicates
oxides & carbonates
sulfides & sulfates
Oxides and Carbonates
• Oxides – metals combined with oxygen
Iron (hematite-magnetite) chromium (chromitite) manganese (pyrolusite) tin (cassiterite) uraninum (uraninite)
• Most metals come from these ores
Hemetite From yahoo images
Oxides and Carbonates
• Carbonates – minerals composed of carbonate ion CO3
Calcite – calcium carbonate CaCO3
Dolomite – calcium and magnesium carbonate CaMg(CO3)2
These two make up limestone calcite From yahoo images