Mineral

A mineral is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties.

What is a Mineral?

Each mineral is characterized by a unique set of these 5 physical properties

• Naturally occurring
• Inorganic
• Solid element or compound
• Definite chemical composition
• Regular internal crystal structure

Identifying Minerals

• Best to use technology to analyze the chemical composition and the crystal structure

• Some are easily identifiable based on physical properties

• Colour: Visible hue of a mineral (but not the best property)

• Streak: Colour left behind when mineral is scraped on unglazed porcelain

• Hardness: Scratch-resistance (Mohs hardness scale)

• Crystal form: External geometric form

• Cleavage: Way it breaks when struck

• Luster: Manner in which light reflects off surface of a mineral

• Density; Magnetic; Fizzes when acid dropped on it; Tastes like salt

Color is not unique

Types of Minerals

• Nonsilicates grouped by some chemical component or characteristic ⇒ often same negatively charged ion or group of atoms
• Carbonates - contain CO3 and dissolve easily, especially in acid; Calcite most abundant and most important in this group!
• Sulfates - SO4; Useful for building materials
• Sulfides - S; Pyrite (Fool’s gold); Host for many metallic ores (e.g., Pb, Cu, Zn)
• Oxides - any metal combined with oxygen; Iron and aluminum ores
• Native elements - minerals composed of single element
  • Carbon as diamond and graphite (pencils!)
  • Copper, gold, silver, or platinum

Minerals are worth looking at…

• over 4400 minerals have been identified, but only a few hundred are common enough to be generally important to Geology (rock-forming or money)

Related

• Rocks are formed from minerals