Economic Ores - Mostly metals
Intro points An ore is a naturally occurring solid material from which a metal or valuable mineral can be profitably extracted. Gangue is the commercially valueless material in which ore is found. Tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Economic minerals include metals, rocks and hydrocarbons (both solid and liquid) that are extracted from the earth by mining, quarrying and pumping. Only gold, silver, copper and the platinum metals occur in nature in large amounts. Almost all are sulfides, oxides and carbonates easier to extract metal
Extraction of Metals from their ores Metals below carbon in the figure can be extracted by roasting the ore with carbon after first heating mineral in air or oxygen e.g. ZnS + O 2 à ZnO + SO 2 then ZnO + C à Zn + CO 2 Metals above carbon are much more difficult (read a lot more expensive) to extract. e.g. Al
Bauxite Major ore of Aluminum Al(OH) 3 Also present are kaolinite and iron oxides Extraction of Al requires electricity and molten rock!!
Bornite Copper ore Cu 5 FeS 4 crystallizes in the orthorhombic system peacock mineral
Chalcocite By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10158499 A copper ore CuS 2 Monoclinic Often as hydrothermal deposits below other weathered Cu ores
Cassiterite This is the main tin ore Here with muscovite Separated by sg 3 vs 7 SnO2 tetragonal By CarlesMillan - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20842834
Chromite Source of Cr (Fe,Mg)Cr 2 O 4 Found in Yukon, often with Pt
Cinnabar By JJ Harrison (jjharrison89@facebook.com) - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7185993 Cinnabar on dolomite(camg(co3)2) source of Hg HgS Trigonal Separated by s.g. 3 vs 8 red pigment/paint vermilion
Cobaltite By User Tor Svensson - Photo taken by me, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3634617 Co ore CoAsS in hydrothermal deposits and metamorphic rocks. Orthorhombic However, cobalt often found and mined with Ni
Galena By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10448612 This is galena in a fluorite bed. Main ore of lead PbS Cubic Separation by s.g.
Ilmenite By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10136807 An ore of Ti FeTiO3 trigonal
Rutile Another Ti mineral. TiO 2 Twinned clusters of golden acicular rutile crystals growing in dark shiny hematite rutile crystals are v-twinned every 60 degree angles resulting in a star-shaped cluster Pigment white
Magnetite By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10139390 Important ore of iron Fe 3 O 4
Sphalerite By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10169459 On quartz This is gemstone quality from Hunan province in China crystal is about 2cm across ZnS usually found with significant iron
Witherite By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10161629 2 crystals of Witherite on calcite BaCO 3 Orthorhombic
A few gemstones
Diamond Diamonds occur most often as euhedral or rounded octahedra and twinned octahedra known as macles.
Sapphire By CRPeters - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10845112 Corundum Al2O3 with metal impurities. Typically blue but can get other colours except for red eg this yellow sample from Montana
Ruby By Rob Lavinsky, irocks.com CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10474216 Corundum with trace Cr
Garnet Semi-precious gemstone This particular sample is Ca 3 Fe 2 (SiO 4 ) 3
And now a rock Granite By I, Friman, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2421115 a type of felsic intrusive igneous rock granular phaneritic texture Composition: feldspar quartz mica (biotite, muscovite) amphibole minerals (hornblende) 20-60% quartz, at least 35% of the total feldspar consisting of alkali feldspar Usually massive (no internal structures), hard and tough. BUILDING MATERIAL
My favorite rock.. Shap granite Lake District of England Photos General: http://www.turnstone.ca/shap2.jpg Xenolith: https://i.pinimg.com/originals/ec/5a/e6/ec5ae6e45804f1e657a61510d77e6f02.jpg
What is a rock? Physical Geology by Steven Earle A consolidated mixture of one or more minerals. Consolidated means hard/strong A mixture of minerals implies the presence of more than one mineral grain, but not necessarily more than one type of mineral. A rock can be composed of only one type of mineral (e.g., limestone is commonly made up of only calcite), most rocks are composed of several different minerals. Can also include other things such as fossils, organic matter etc.
Three types of rock Rocks are classified, by how they are formed, into 3 groups Igneous - from the cooling/crystallization of magma Metamorphic - by alteration of a pre-existing rocks (heat, pressure, chemical action) Sedimentary a. formed by weathering. Fragments of rocks are buried, compressed, and cemented together, or b. formed by precipitation from solution
The Rock Cycle Physical Geology by Steven Earle
Reading.. Pages 60-80 in Physical Geology by Steven Earle (online text)
END J