L1.2: Physical Properties

• PHYSICAL PROPERTIES

  • Hardness
  • Crystal Form or Habit
  • Streak
  • Luster
  • Light Transmission
  • Breakage
  • Specific Gravity
  • Other Properties
• PHYSICAL PROPERTIES

  ● Hardness

  ○ Ability to resist scratching. Mohs hardness scale is used to test the hardness.
• PHYSICAL PROPERTIES

  ● Crystal Form or Habit

  ○ The external shape displayed as it grows; the form reflects the supposedly internal structure of atoms and ions.

  ○ No crystal structure is called amorphous.

  ○ Simplified: It’s like the shape itself is somehow dependent on the atomic structure, so if medj pasquare yung atomic structure parang pasquare din ata yung shape.
• PHYSICAL PROPERTIES

  ● Streak

  ○ Real color of the mineral can be obtained by streaking to see the color of its powdered form. By scratching it in an unglazed porcelain plate or a "streak plate"
• PHYSICAL PROPERTIES

  ● Luster

  ○ The way it can reflect light from the surface.

  ○ Metallic: opaque and shiny

  ○ Nonmetallic: glassy (vitreous), brilliant, resinous, silky, and pearly.
• PHYSICAL PROPERTIES

  ● Light Transmission

  ○ Opaque: no light is transmitted.

  ○ Translucent: only a small amount of light can pass through.

  ○ Transparent: most of the light can pass through.
• PHYSICAL PROPERTIES

  ● Breakage

  ○ Cleavage: predictable break due to weak bonding and usually in parallel zones.

  ○ Fracture: breaks along a curved surface without definite shape.

  ○ Simplified: If you use a hammer and try to break it, cleavage will often result in a planar and flat. While for fracture, just remember the dude from tiktok who makes an obsidian knife/spearhead.
• PHYSICAL PROPERTIES

  ● Specific Gravity

  ○ The minerals possess a specific gravity that has a close relation to the density of water content in each mineral.

  ○ To get it, divide the final mass by the initial mass. For example 230/80 = 2.875, thus 2.875 is the Specific gravity.
• PHYSICAL PROPERTIES

  ● Other Properties

  ○ Taste

  ○ Odor

  ○ Magnetism

  ○ Fluorescence

  ○ Radioactivity

  ○ Reactivity
• Mohs Hardness Scale

  ● Created in 1824 by Austrian Mineralogist Friedrich Mohs.

  ● Higher number of minerals in the scale can leave a scratch on the lower number of minerals.
• Mohs Hardness Scale

  ● Mnemonic: Terrible Giants Can Find Alligators Or Quaint Trolls Conveniently Digestible (increasing hardness)

  1. Talc
  2. Gypsum
  3. Calcite
  4. Fluorite
  5. Apatite
  6. Feldspar
  7. Quartz
  8. Topaz
  9. Corundum
  10. Diamond