2 FractureFracture is the tendency of a mineral to break along curved surfaces without a definite shape. These minerals do not have planes of weakness and break irregularly
3 CleavageCleavage is the tendency of a mineral to break along smooth planes parallel to zones of weak bonding
4 LusterAdamantine - very gemmy crystalsDull - just a non-reflective surface of any kindEarthy - the look of dirt or dried mudFibrous - the look of fibersGreasy - the look of greaseGumdrop - the look a sucked on hard candyMetallic - the look of metalsPearly - the look of a pearlPitchy - the look of tarResinous - the look of resins such as dried glue or chewing gumSilky - the look of silk, similar to fibrous but more compactSubmetallic - a poor metallic luster, opaque but reflecting little lightVitreous - the most common luster, it simply means the look of glassWaxy - the look of waxLuster is a description of the way light interacts with the surface of a crystal. This is how you would tell someone how a mineral looks. It has nothing to do with color or shape, but is related to transparency , surface conditions, crystal habit and index of refraction.Vitreous Dull Resinous Adamantine Metallic Silky
5 StreakThe streak of a mineral is the color it displays in finely powdered form. The streak maybe completely different from the color of the hand specimen. One of the simpliest ways of determining the strak of a mineral is to rub a specimen across a piece of unglazed porcelain known as a streak plateMagnetite – Black StreakAmphibole – grey/green streakHematite – red/brown streak
7 Vesicular textureGlassy textureTextureMinerals may be rough, like sand, others may be smooth or chalky. Run your fingers on the rock. What does it feel like.rough & crystalline texturePegmatitic Texture – big grains
8 Specific GravityDensity or specific gravity is the ratio of the weight of a substance to the weight of an equal volume of water.Density = Weight/Volume
9 Crystal SystemCrystal shape can be helpful in identification. Most minerals have a crystalline structure and can form perfect crystals if allowed to grow in an unrestricted space. Crystal faces resemble cleavage faces because they are flat and reflect light as a single plane, but they are different from cleavage surfaces because crystals have complex geometric shapes. Perfect crystals are rare and are seldom encountered.
10 Crystal System 2 CRYSTAL SYSTEM - AXES LENGTHS - AXIAL ANGLES CUBIC All equal All 90TETRAGONAL a=b not = c all 90HEXAGONAL two are equal are 90, one 120ORTHORHOMBIC all unequal all are 90MONOCLINIC all unequal two are 90TRICLINIC all unequal none are 90IsometricMonoclinicHexagonalOrthorhombicTriclinicTetragonal
11 Color Quartz Quartz Quartz Quartz Malachite Pyrite Olivine Limonite Minerals have the same chemical composition but small variations of the quantity and distribution of some elements will give the same mineral different colors.Quartz Quartz Quartz QuartzMalachite Pyrite Olivine Limonite
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