Good morning!!! Minerals Calisaan, Naki, Refuerzo EARTH — one of the four terrestrial planets in the Solar System GEOSPHERE — one of the four interacting spheres that allow life to exist — refers to the solid Earth — composed of rock and regolith which are essentially aggregates of various minerals Characteristics of Minerals Refuerzo Back to Agenda 1. Naturally-occuring — Minerals exist naturally. — Steel and synthetic diamonds are created artificially, and therefore, are not minerals. shine bright like a diamond 2. Inorganic — Minerals are limited to substances formed through inorganic processes, and exclude materials derived from living organisms which involved organic processes. — Coal, which is composed of remains of plants and other inorganic compounds, is not a mineral. 3. Solid — All liquids and gases (even those that are naturally formed such as petroleum) are not considered minerals. 4. Definite Chemical Composition — The chemical composition of minerals should express the exact chemical formula with the elements and compounds in specific ratios. — The only exception is the atomic substitution, which is characteristic of certain minerals. 5. Ordered Internal Structure — The atoms in minerals are organized in regular, repetitive geometric patterns or crystal structure. — Volcanic glass, even if it is formed naturally, is not considered a mineral because it is amorphous and has no form. Obsidian Pearl Amber Opal Mineraloids — substances that fulfill all the requirements but do not have an ordered internal structure Composition of Minerals Calisaan SILICATES — primarily silicon oxygen tetrahedrons - major rock forming minerals Ex: Olivine and Quartz OXIDES —metal cations bonded to oxygen anions Ex: Magnetite and Hematite SULFIDES —metal cation bonded to sulfide —common ore minerals along with oxides Ex: Galena and Pyrite SULFATES —metal cation bonded to the anionic group Ex: Gypsum HALIDES —are composed of a halogem ion Ex: Halite and Flourite CARBONATES —presesnce of carbonic ion —calcium or magnesium Ex: Calcite and Dolomite NATIVE METALS —single metal Ex: Copper and Gold Crystal Structure of Minerals Refuerzo Back to Agenda Crystal Structure — is dependent on the chemical composition of the mineral — Minerals that have similar chemical compositions often share the same crystal structure and generally belong to the same crystal system. — There are six crystal systems used in grouping minerals based on structure: Isometric Orthorhombic Tetragonal Monoclinic Hexagonal Triclinic Physical Properties of Minerals Calisaan, Naki, Refuerzo Back to Agenda Crystal Form and Habit Since minerals have a definite chemical composition, it forms a definite structure which crystallizes into a specific crystal form. The outward appearance of the minerals is referred to as the crystal form, while on the other hand, the characteristic external shape is called the crystal habit. Crystal Habit — Crystal habit is the tendency for specimens of a mineral to repeatedly grow into characteristic shapes. These shapes are influenced by the atomic structure of the mineral, but they can also be influenced by the environment of crystal growth. Tabular Drusy Acicular Encrusting Crystal Habit Reniform Cleavage -The tendency of a mineral to break along specific internal planes of weakness . -Determined by atomic arrangement of the minerals Factors -Quality -Number of sides exibiting cleavage Category of Quality -excellent -good -poor -indistinct -none Fracture -Is a break in a mineral that is not along a cleavage plane -it is not determined by the structure of the mineral. conchoidal uneven even hackly Types of Fractures splintery Luster — The luster of a mineral describes the appearance of light as it is reflected off its surface. — A mineral may be described as metallic, like that of a polished metal. — Alternatively, it may be described as nonmetallic, which can be vitreous (like glass), resinous (like resin), pearlescent, silky, greasy, earthy, and dull. Metallic Luster Nonmetallic Luster Vitreous Greasy Resinous Pearlescent Silky Dull Color -is not a reliable feature. -it can be altered by chemical impurities within its structure -minerals come in many colors -many have the same color -some colors change Streak -is the color of a mineral in powdered form -this can be done by scraping the corner of the sample across a streak plate -it is not affected by weathering Hardness — The hardness of a mineral is a measurement of the strength of the chemical bonds in its structure. It can be measured by scratching it with another mineral or a reference material with known hardness. The Mohs Scale The Mohs scale of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the German geologist and mineralogist Friedrich Mohs. The Mohs Scale Density — Density or Specific gravity is the ratio of a measure of a mineral's mass and volume. It is the weight of a mineral relative to the weight of an equal volume of water. Common Rock- Forming Elements The abundance and variety of minerals are controlled by their chemistry, which is dependent on elemental abundances on Earth. About 98% of Earth's crust is composed of eight elements. Back to Agenda Mineral Graphite Galena Lust er M e t a l l i Colors Silver to gray Metalli c silver Hard ness 1-2 2.5 Cle ava ge Fra ctu re Characterist ics Uses Composition ✓ Black streak, greasy feel Pencil lead, lubricant C ✓ Very dense, gray-black streak, Ore of lead PbS Mineral Magnetite Pyrite Lus ter m e t a l l i c Colors Ha rdn ess Black to silver 5.5 6.5 Brassy 6.5 Cle ava ge Fr act ur e Characteristics Uses Compositi on ✓ Magnetic, black streak Ore of iron Fe3O4 ✓ Green-black streak, cubic crystals Ore of sulfur FeS2 Mineral Lus ter Colors Ha rdn ess Hematite E i t h e r Metallic silver to earthy red 16.5 Cle ava ge Fr act ur e ✓ Characteristics Red-brown streak Uses Compositi on Ore of iron Fe2O3 Mineral Lust er Talc Sulfur no nm eta llic Colors white to green yellow to amber Hard ness 1 2 Cle ava ge Fra ctu re ✓ ✓ Characterist ics Uses Composition Greasy feel talcum powder, soapstone Mg3 Si4 O10 (OH)2 Easily melted, may smell vulcanize rubber, sulfuric acid S Mineral Gypsum (selenite) Muscovite mica Lust er no nm eta llic Colors white to pink to grey colorless to yellow Har dne ss 2 22.5 Cle ava ge ✓ ✓ Fra ctu re Characteristics Uses Compositi on easily scratched by fingernail plaster of paris and drywall CaSO4 2H2O electrical insulator KAI3SI3 O10(OH) 2 flexible in thin sheets Mineral Halite Biotate mica Lust er no nm eta llic Colors Hard ness Cle ava ge Fra ctu re Characterist ics Uses Composition food additive, melts ice NaCl electrical insulator K(Mg,Fe)3AlSi3 O10(OH)2 colorle ss to white 2.5 ✓ cubic cleavage, salty taste black to dark brown 2.5 3 ✓ flexible in thin sheets Mineral Calcite Dolomite Lust er no nm eta llic Colors colorless /variable colorless /variable Har dne ss Cle ava ge Fra ctu re Characteristics Uses Compositi on CaCO3 CaMg (CO3)2 3.5 ✓ bubbles with acid cement, polarizing prisms 4 ✓ bubbles with acid when powdered source of magnesium Mineral Fluorite Pyroxene (augile) Lust er no nm eta llic Colors colorle ss/vari able black to dark green Hard ness Cle ava ge 4 5 -6 Fra ctu re Characterist ics Uses Composition ✓ cleaves in 4 directions hydroflu oric acid CaF2 ✓ cleaved in 4 directions in 90 degrees mineral collection s (Ca,Na)(Mg,Fe,Al) (Si,Al)2O6 Mineral Amphiboles (hornblende) Potassium feldspar (orthoclase) Lust er no nm eta llic Colors black to dark green white to pink Har dne ss 5.5 6 Cle ava ge Fra ctu re Uses Compositi on ✓ cleaves at 56 and 124 degrees mineral collections Ca,Na(M g,Fe)4 (Al,FeTi) 3Si6022( O,OH)2 ✓ cleaves in 2 directions of 90 degrees ceramics and glass KalSi3O 3 Characteristics Mineral Plagioclase feldspar (Na-Ca fledspar) Olivine Lust er no nm eta llic Colors white to grey green to grey/ brown Hard ness 6 6.5 Cle ava ge Fra ctu re ✓ ✓ Characterist ics Uses Composition cleaves in 2 directions, striations visible ceramics, glass (Na, Ca) AlSi₃ O₈ commonly light green and granular furnace bricks, jewelry (Fe, Mg)₂ SiO₄ Mineral Lust er Quartz Garnet (almandine) no nm eta llic Colors colorless /variable dark red to green Har dne ss 7 7 Cle ava ge Fra ctu re Characteristics Uses Compositi on ✓ glassy luster, may form hexagonal crystals glass, jewelry, electronics SiO₂ ✓ glassy luster, seen as red grains in NYS metamorphic rocks jewelry, abrasives Fe₃Al₂Si₃ O₁₂ THANK YOU VERY MUCH! Have a great week! — Calisaan, Naki, & Refuerzo —
