Earth Science (4 ppts)

• What are the characteristics that define a mineral?

  Minerals are naturally-occurring, inorganic, solid at room temperature, have a regular crystalline structure, and have a defined chemical composition.
• How do minerals form?

  Minerals form through various geological processes, such as crystallization from magma or precipitation from solutions.
• What is the difference between minerals and rocks?

  Minerals are the building blocks of rocks, while rocks are made up of one or more minerals.
• What are the key differences between minerals and rocks?

  Minerals have a specific chemical formula, a crystalline structure, and form through specific processes, while rocks can vary in composition and formation processes.
• Give an example of a rock and its mineral components.

  Granite is a rock composed of quartz, feldspar, and mica minerals.
• What are the key physical properties used to identify minerals?

  • Color
  • Streak
  • Luster
  • Hardness
  • Cleavage and fracture
  • Crystal shape
  • Specific gravity
• Why is color considered a tricky property for identifying minerals?

  Color can be misleading as many minerals can occur in various colors due to impurities.
• What is the streak of a mineral?


  The streak is the color of a mineral's powder, determined by scratching the mineral on an unglazed porcelain plate.
• Why is streak often more reliable than a mineral's apparent color?

  Streak is often more reliable because it reflects the true color of the mineral in powdered form, which is less affected by impurities.
• What are the characteristic streaks of hematite and pyrite?

  Hematite has a red-brown streak, while pyrite has a greenish-black streak.
• What does luster describe in minerals?

  Luster describes how light reflects off a mineral's surface.
• What are the two main categories of luster?

  The two main categories of luster are metallic and non-metallic.
• What are some examples of non-metallic lusters?

  Non-metallic lusters include vitreous (glassy), pearly, silky, resinous, and earthy.
• What is the Mohs Hardness Scale used for?

  The Mohs Hardness Scale measures a mineral's resistance to scratching, ranging from 1 (softest) to 10 (hardest).
• What is the hardness of talc and diamond on the Mohs scale?

  Talc is rated 1 (softest) and diamond is rated 10 (hardest) on the Mohs scale.
• How can you test a mineral's hardness?

  You can test a mineral's hardness by trying to scratch it with objects of known hardness.
• What is the difference between cleavage and fracture in minerals?

  Cleavage is the tendency of a mineral to break along flat, smooth surfaces, while fracture is an irregular breaking pattern when a mineral doesn't cleave.
• What determines the type of cleavage in a mineral?


  The type of cleavage is determined by the mineral's internal structure.
• What are the types of cleavage in minerals?

  Types of cleavage include one direction (e.g., mica), two directions (e.g., feldspar), and three directions (e.g., calcite).
• What are the types of fracture in minerals?

  Fracture types include conchoidal, splintery, and earthy.
• What is an example of a mineral with no cleavage but a conchoidal fracture?

  Quartz has no cleavage but exhibits a conchoidal fracture.
• What does crystal shape refer to in minerals?

  Crystal shape refers to the external form of a well-formed mineral, determined by the internal atomic structure.
• What are some common crystal shapes of minerals?

  Common crystal shapes include cubic (e.g., pyrite, halite), hexagonal (e.g., quartz), octahedral (e.g., fluorite), rhombohedral (e.g., calcite), and monoclinic (e.g., gypsum).
• How does the internal atomic structure influence crystal shape?

  The internal atomic structure determines the arrangement of atoms, which influences the external form of the mineral's crystal shape.
• What is specific gravity in relation to minerals?

  Specific gravity is the ratio of a mineral's weight to the weight of an equal volume of water, and it measures density.
• How can specific gravity be estimated?

  Specific gravity can be estimated by "heft," which is how heavy a mineral feels for its size.
• What are the specific gravities of quartz, pyrite, and gold?

  Quartz has a specific gravity of 2.65, pyrite has 5.0, and gold has 19.3.
• What are some unique properties that aid in mineral identification?

  Unique properties include magnetism (e.g., magnetite), reaction to acid (e.g., calcite fizzes in dilute hydrochloric acid), fluorescence under UV light, double refraction (e.g., calcite), and taste (e.g., halite tastes salty).
• What is the chemical formula for quartz?


  The chemical formula for quartz is $SiO_2$ (Silicon dioxide).
• What are the properties of quartz?


  Quartz has a hardness of 7 on the Mohs scale, vitreous luster, conchoidal fracture, various colors, and forms hexagonal crystals.
• What are the two main types of feldspar?

  The two main types of feldspar are potassium feldspar and plagioclase feldspar.
• What are the properties of feldspar?

  Feldspar has a hardness of 6-6.5 on the Mohs scale, vitreous to pearly luster, two directions of cleavage at 90 degrees, and is often white, pink, or gray.
• What are the two common types of mica?

  The two common types of mica are biotite (dark) and muscovite (light).
• What are the properties of mica?

  Mica has a hardness of 2-2.5 on the Mohs scale, pearly to vitreous luster, and perfect cleavage in one direction, forming thin sheets.
• What is the chemical formula for calcite?

  The chemical formula for calcite is $CaCO_3$ (Calcium carbonate).
• What are the properties of calcite?

  Calcite has a hardness of 3 on the Mohs scale, vitreous to pearly luster, perfect cleavage in three directions (rhombohedral), and reacts with dilute hydrochloric acid.
• What are the properties of hornblende?

  Hornblende has a hardness of 5-6 on the Mohs scale, vitreous to silky luster, and two directions of cleavage at 124 and 56 degrees.
• What are the properties of olivine?

  Olivine has a hardness of 6.5-7 on the Mohs scale, vitreous luster, conchoidal fracture, and is typically olive green.
• What is the chemical formula for olivine?

  The chemical formula for olivine is $(Mg,Fe)_2SiO_4$.
• What are the steps to identify a mineral?

  1. Observe color and luster
  2. Test hardness
  3. Check for cleavage or fracture
  4. Observe crystal shape if visible
  5. Test streak
  6. Consider other distinctive properties