Minerals

Fracture/Cleavage

"How it breaks." -Cleavage: the mineral breaks to form distinct planar surfaces -Fracture: the mineral breaks into rough edges -Conchoidal Fracture: the mineral breaks into smoothly curving surfaces

Monoclinic Structure Characteristics

3 axes uneven in length. 2 axes intersect at a 90° angle while the third axis intersects the others obliquely. This crystal system has the most minerals, with about 1/3.

Orthorhombic Structure Characteristics

Aka "the brick." 3 axes, all varying in length, at right angles to each other.

Inorganic

Almost all minerals are inorganic (not containing any Hydrogen-Carbon bonds). Mineralogists have made exceptions to about 30 organic substances that are considered organic

Crystalline Structure

An ordered atomic arrangement. Opal is an exception

Carbonates

Elements such as Ca or Mg bond to a carbonate group, CO3^2-. Examples include: -Calcite (CaCo3) -Dolomite (CaMg[CO3]2) -Malachite/Azurite

Inosilicates

Chain silcates that make monoclinic crystals. There are 2 varieties, single-chain and double-chain.Pyroxene group has a single-chain structure. Examples include: -Augite While Amphibole group has a double-chain structure: -Hornblende

Streak

Color of the mineral powder

Sulfides

Consist of a metal cation bonded to a sulfide anion (S^2-). Many sulfides have a metallic luster and are considered ore minerals. Examples include: -Galena (PbS) -Pyrite (FeS2) -Chalcopyrite

Sulfates

Consist of a metal cation bonded to the SO4^2- group.Many form by precipitation out of water near or at the earth's surface. Examples include: -Gypsum (CaSO4 · 2 H2O) -Barite

Oxides

Consist of metal cations bonded to oxygen anions. Examples include: -Hematite (Fe2O3) -Magnetite (Fe3O4) -Limonite -Corundum

Native Elements

Consist of pure masses of a single element. Metal atoms are bonded by a metallic bond. Examples include: -Copper (Cu) -Gold (Au) -Silver (Ag) -Mercury (Hg) -Diamond (C) -Sulfur

Silicates

Contain the silica tetrahedron. Most abundant of all mineral groups. The silica tetrahedron form several types of linkages which allow for 7 structural groups: -Nesosilicates -Inosilicates -Phyllosilicates -Tectosilicates -Sorosilicates

Halides

Contains a halogen anion. Examples include: -Halite (NaCl) -Fluorite (CaF2)

Phosphates

Contains a phosphate anion group, PO4. Examples include: -Apatite (Ca3[F3Cl][PO4]3)

Definite Chemical Composition

It is possible to write a chemical formula for a mineral.

Homogenous Solid

Maintains its shape indefinitely. There are 2 exceptions :-Mercury (Hg) -Water

Color

Many minerals vary in color, but some are obvious because of their color. Eg. sulfur

Hardness

Measure of a mineral's relative ability to resist scratching, therefore representing the resistance of bonds in the crystal structure to being broken.

Formed By Geologic Processes

Occurring naturally on or in the earth. Examples include chemical reactions, freezing of molten rock, and precipitation.

Morphing Shapes

Occurs when the edges are "cut off." Seen in fluorite and raw diamonds

Luster

The way a mineral surface scatters light. Minerals are described as metallic or non metallic. Words used to describe minerals with non metallic luster include: -silky -glassy; vitreous -satiny -resinous -pearly -earthy

Biogenic Minerals

This term emphasizes a mineral's origin being from a living organism. Eg. calcite in a clam shell

Hexagonal Crystal System

eg. apatite, niccolite, quartz, zincite, calcite, dolomite, tourmaline, corundum, hematite and more

Monoclinic Crystal System

eg. augite, biotite, gypsum, hornblende, malachite, muscovite, orthoclase, selenite, and many others

Orthorhombic Crystal Structure

eg. azurite, barite, sulfur, olivine, topaz and others

Tetragonal Crystal Structure

eg. cassiterite, chalcopyrite, scheelite, thorite, idocrase, wulfenite, zircon, and others

Isometric Crystal Structure

eg. diamonds, gold, platinum, copper, orgentite, chromite, magnetite, sphalerite, galena, halite, tetrahedrite, garnets, spinel, cuprite, pyrite, bornite, uraninite and others

Triclinic Crystal System

eg. plagioclase, microcline, turquoise and others

Silicate Lab Samples

-Augite (Ino) -Biotite (phyllo) -Chlorite (phyllo) -Hornblende (Ino) -Kaolonite (phyllo) -Muscovite (phyllo) -Olivine (neso) -Orthoclase (tecto) -Plagioclase (tecto) -Quartz (tecto) -Tlac (phyllo) -Tourmaline (tecto) -Topaz (neso) -Garnet (neso) -Beryl

Luster of Specific Minerals

-Galena: metallic -Quartz: vitreous -Pyrite: metallic -Calcite: vitreous -Muscovite: vitreous, pearly -Biotite: virteous, pearly -Hematite: earthy

Mineral Classes

-Oxides -Sulfides -Sulfates -Halides -Carbonates -Native Elements -Phosphates -Silicates

Most Common Elements in the Earth's Crust

-Oxygen (O): 46.6% -Silica (Si): 27.7% -Aluminum (Al): 8.1% -Iron (Fe): 5.0% -Calcium (Ca): 3.6% -Sodium (Na): 2.8% -Potassium (K): 2.6% -Magnesium (Mg): 2.1%

Most Abundant Minerals in the Earth's Crust

-Quartz (SiO2) -Orthoclase (KAlSi3O8)

Mineral ID Useful Properties

-color -streak -fracture/cleavage -specific gravity -hardness -luster -crystal form -magnetism -effervescent

Tetragonal Structure Characteristics

3 axes where the horizontal axes are the same length and the vertical axis (c-axis) is longer or shorter, giving it a stretched or flattened appearance. Axes are at right angles to each other. This crystal system has the fewest minerals

Triclinic Structure Characteristics

3 axes, all of different lengths and none of them intersect at a 90° angle. This structure is the most difficult to recognize. It is the least symmetrical, "everything leans."

Hexagonal Structure Characteristics

4 axes where 3 of them are of equal length and lie at 60° angles from eachother. The horizontal axis is a different length and placed at a 90° angle to the rest.

Rhombahedral Structure Characteristics

A branch of hexagonal crystal structure. Often confused with triclinic crystals, but up close inspection, it exhibits a perfect 6-fold rotation. Minerals include corundum (rubies and sapphires), beryl (emeralds) and tourmaline

Tectosilicates

Framework silica structure. Examples include: -Quartz -Na-Feldspar

Mineral

From text: Naturally occurring solid, formed by geologic processes, that has a crystalline structure a definable chemical composition. Almost all minerals are inorganic

Nesosilicates

Independent tetrahedral groups. The Si tetrahedron don't touch each other, but are separated by other, usually metallic, ions. The most common silicate. Examples iclude: -Olivine -Topaz

Know the crystal systems for the following minerals

Quartz - hexagonal Calcite - hexagonal/rhombohedral Pyrite - isometric Diamond - isometric Fluorite - isometric Barite - orthorhombic Microline (Orthoclase) - monoclinic Corundum - hexagonal/rhombohedral Gypsum/Selenite - monoclinic Halite - isometric

Specific Gravity

Represents the density of a mineral, as represented by the ratio between the weight of a volume of a mineral and the weight of an equal volume of water at 4 degrees celsius

Phyllosilicates

Sheet silica structure. Three O ions of each tetrahedron are shared with adjacent tetrahedra. Perfect cleavage occurs parallel to the plane of the sheet. All micas and clays have this structure.Examples include: -biotite -muscovite -talc -chlorite -kaolonite

Silica tetrahedron

SiO4^4-, four oxygen atoms surround a single silicon atom. It is the building block of silicate minerals

Isometric Crystal Characteristics

The most symmetrical crystal system. Crystal has 3 axes which are at equal in length and at right angles to each other. Contains many recognizable shapes including cubes, octahedrons and morphing shapes.

Crystal Form (or Crystal Habit)

The shape of a single crystal with well formed crystal faces. The habit depends on the internal arrangement of atoms in the crystal

Naturally Occurring

True minerals are formed in nature. Although they can be synthesized in in a lab, in geology, a mineral is a mineral if it occurs naturally.