Minerals

• Minerals


  Naturally occurring inorganic elements
• Minerals


  • Compound having an orderly internal structure and characteristic chemical composition
• Minerals are inorganic
• Ways minerals form

  • When salt water evaporates
  • When chemical came out of hot fluids
  • When hot gases or molten rocks cool
  • When heat or pressure-change pre-existing minerals
• Mineral formation

  1. Atoms moving randomly in a fluid

  2. Forming from volcanic gases

  3. Forming from sediment formation

  4. Forming from oxidation

  5. Forming from crystallization from magma

  6. Forming from deposition from saline
• Minerals form in a variety of different ways
• Definition – four part definition

  1.  Naturally occurring
  2.  Inorganic substance (non-living)
  3.  Crystalline solid
  4.  Definite chemical composition      
• There are substances that meet 3 of the 4 criteria, and are called mineralloids    Example: Opal – does not have an orderly arrangement of atoms
• • More than 3,500 different minerals have been identified- Minerals combine to form all rocks on Earth  Rock type depends on mineral composition 20 minerals combine to form 95% of all rocks on Earth.
• dD

  • Naturally occurring substance
  • Crystalline structure
  • Various colors
  • Different hardness levels
• Diamond


  • Hardest mineral
• Quartz


  • One of the most abundant minerals
• Minerals can exhibit fluorescence
• C. Physical Properties - All minerals have at least 9 physical properties that can be used to define, describe, and identify them as unique minerals.
• 1. Color – every mineral has some color and some are found in multiple colors  could be very helpful and distinctive, or could be very ambiguous
• 2. Luster – the manner in which a mineral reflects light

  Glassy – reflects light like a piece of glass does 

  Metallic – reflects light like a piece of metal does
• 3. Streak – the color of the pulverized powder of a mineral
• The color could be different from the crystal’s color, and is always distinctive
• 4. Hardness – the scratchability of a mineral, or a mineral’s durability Uses the Moh’s Hardness scale with a rating system of 1-10

  *1 = very soft *10 = hardest substance
• 5. Crystal shape / External Crystal Form / Crystal Systems

   a set of faces that have a definite geometric relationship to each other
• 1. Isometric – most symmetrical Three axes of equal length All axes at right angles to each other
• 2. Tetragonal – similar to isometric Three axes, two equal length, the third is longer All axes at right angles to each other
• 3. Hexagonal Three equal axes in the same plane Intersect at angles of 60 degrees A fourth axis is at a right angle to the other three
• 4. Orthorhombic Three axes all unequal to each other All axes intersect at right angles
• 5. Monoclinic Two non-equal axes at right angles to each other A third axis is inclined to one of the first two
• 6. Triclinic Three axes All axes are inclined with respect to each other
• 6. Mineral Cleavage – the ability of a mineral to break, when struck along specific planes

  Based on the bonding between atoms Where the bonds are weakest = breakage plane
• minerals Can have no cleavage (example = quartz)
• Can have 1 plane of cleavage (ex. = Biotite)
• minerals can can have multiple planes of cleavage
• Fracture The way a substance breaks where not controlled by cleavage Minerals with no cleavage generally break with irregular fracture
•  If minerals break with curved fracture surfaces, it is called concoidal fracture This is seen in glass, the igneous rock Obsidian, and the mineral Quartz
• Specific Gravity – the density of a mineral - Density = mass of an object / volume of the object - The ratio of the mass of an object to the mass of an equal volume of water - The density of pure water = 1 g / mL - If the density of the object is < 1 = lighter than water, and will float to some degree - If the density of the object is > 1 = heavier than water, and will sink
• A.Taste – a few minerals have a characteristic taste Halite tastes like salt b.
• b. Odor – a few minerals have a characteristic odor Clay minerals have an “earthy” smell
• c. Striations – straight parallel lines on the flat surface of the cleavage directions
• d. Magnetism – some minerals with large amounts of iron oxide are attracted to magnets
• e. Double Refraction – a clear mineral placed over an image will show 2 images by the light being split as it enters some crystalline minerals Example - Calcite
• f. X-ray fingerprints – when x-rays are directed through minerals, the x-rays are deflected out at specific angles  Each mineral has a specific pattern
• g. Chemical tests – how do minerals react to specific chemicals Example – Carbonate minerals (calcite) will react to weak hydrochloric acid, they will fizz to produce carbon dioxide (CO2) gas