ESS_Q1_M3

• Classes of minerals

  • Native Elements
  • Silicates
  • Oxides
  • Sulfides
  • Sulfates
  • Halides
  • Carbonates
  • Phosphates
  • Mineraloids
• Minerals


  • Are naturally occurring substances harnessed and used by humans daily.
  • Crystalline solids w/ definite shape and structure.
• Physical properties of minerals

  • Habit
  • Luster
  • Cleavage and fracture
  • Hardness
  • Color
  • Streak
• Crystal Habit


  The overall shape or growth pattern of the mineral
• Types of crystal habit

  • Equant (three dimensions have about the same length, like a cube or sphere)
  • Elongate (prismatic or prism-like crystals that are thicker than a needle)
  • Platy (flattened and thin crystal like a plate)
• Luster


  The appearance of a mineral when light is reflected from its surface
• Types of luster

  • Metallic (opaque and very reflective)
  • Nonmetallic (dull, silky, greasy, pearly)
• Cleavage


  The tendency of minerals to break along very smooth, flat and shiny surfaces
• Fracture


  The way a mineral breaks along random, irregular surfaces
• True or False?

  
  

  Some minerals break only by fracturing, while others both cleave and fracture

  
  

  True
• Examples of cleavage directions

  • Biotite and mica (one direction)
  • Orthoclase (two directions)
  • Galena (three directions)
  • Fluorite (four directions)
• Hardness


  A measure of the mineral's resistance to scratching
• Mohs Hardness Scale

  • Talc (1)
  • Gypsum (2)
  • Fingernail (2.5)
  • Calcite (3)
  • Copper penny (3.5)
  • Fluorite (4)
  • Apatite (5)
  • Steel knife blade/glass plate (5.5)
  • Orthoclase feldspar (6)
  • Quartz (7)
  • Topaz (8)
  • Corundum (ruby) (9)
  • Diamond (10)
• Color


  One of the most obvious properties of a mineral but not reliable alone
• Streak


  The color of the mineral in its powdered form, which may or may not be the same color as the mineral
• Streak is a more reliable property than color as it shows the true color of minerals.
• Additional physical properties of minerals

  • Magnetism
  • Striations
  • Specific Gravity
  • Taste, Odor, Feel
• Chemical properties of minerals


  Show the presence and arrangement of atoms in minerals. Used to identify how minerals react to certain substances
• Examples of chemical properties

  • Reaction with acid (e.g. calcite effervesces with hydrochloric acid)
  • Toxicity (e.g. cinnabar)
  • Solubility in water (e.g. halite)
  • Formation of sulfuric acid when exposed to air and water (e.g. metallic sulfide minerals)
  • Radioactivity (e.g. uranium and thorium containing minerals)
• Native elements


  Naturally occurring in nature in an uncombined form with a distinct mineral structure
• Silicates


  Largest group of minerals, contains silicon and oxygen, with some aluminum, magnesium, iron and calcium
• Oxides


  Formed from the combination of a metal with oxygen, ranging from dull ores to gems
• Sulfides


  Made of compounds of sulfur usually with a metal, tend to be heavy and brittle
• Sulfates


  Made of compounds of sulfur combined with metals and oxygen, tend to be soft and translucent
• Halides


  Form from halogen elements like chlorine, bromine, fluorine, and iodine combined with metallic elements, very soft and easily dissolved in water
• Carbonates


  Made of carbon, oxygen, and a metallic element
• Phosphates


  Often formed when other minerals are broken down by weathering, often brightly colored
• Mineraloids


  Substances that do not fit neatly into one of the eight mineral classes
• Specific gravity


  The weight of the mineral divided by the weight of an equal volume of water
• Color


  The most obvious property of a mineral
• Mineraloid


  Substances that do not fit neatly into one of the eight mineral classes
• Silicate


  The largest group of minerals
• Habit


  The overall shape or growth pattern of the mineral
• Carbonate


  Minerals that are made of carbon, oxygen, and a metallic element
• Fracture


  When a mineral breaks along random, irregular surfaces
• Hardness


  The measure of the mineral's resistance to scratching
• Given the list of minerals below, what is the correct arrangement from hardest to softest according to Moh’s Scale?

  (1) Quartz, (2) Calcite, (3) Fluorite, (4) Gypsum

  1, 3, 2, 4
• Angela tests a mineral sample by scratching it to white and black porcelain plate to determine its true color. What property of minerals did she test?

  Streak
• James Dana developed a classification scheme for minerals. What is the basis of his classification?

  Chemical composition
• What group of minerals is most common in the earth's crust?

  Silicates