Rocks vs Minerals

Rocks vs Minerals

• Rocks are solids found in the earth's crust, but are different from minerals
• Minerals are naturally occurring substances with unique chemical and physical properties
• Minerals are inorganic, multicolored, have a specific structure, and are defined by their chemical composition

Mineral Definition

• Minerals are inorganic uniform chemical compositions of a solid that have a crystalline internal structure and occur naturally
• Minerals can be made from multiple types of elements or just one
• Minerals can be vast or very small, like a grain of sand
• Example of a mineral: Salt (NaCl)

Classifying Minerals

• Minerals are classified by their chemical composition and crystalline structure
• Other ways to characterize minerals include examining color, density, hardness, streak, luster, and solubility
• Geologists classify crystal structures by counting the number of sides, measuring the angles, and observing cleavage and fracture
• Three main types of crystalline structures:
  • Body-Centered Cubic (BCC)
  • Hexagonal Close-Packed (HCP)
  • Cubic Close-Packed (CCP)

Rock Definition

• A rock is a solid interconnected collective of two or more crystalline minerals
• Rocks are usually made up of various types of mineral grains, held together in one solid form
• Rocks do not always have a repeating arrangement of atoms like minerals do

Classifying Rocks

• Rocks are classified based on how they are formed
• Rocks are made through the rock cycle which either creates new rocks or recycles old rocks
• Three main rock classifications:
  • Igneous
  • Sedimentary
  • Metamorphic
• Igneous rocks are made from hot magma that cools to create rock
• Sedimentary rocks are made over time by pressure from other rocks
• Metamorphic rocks are made from other rocks through chemical reactions and heat

The Rock Cycle

• The rock cycle is the process in which all rock is made or recycled
• Rocks can change from one type to another through geological processes

Is a Rock a Mineral?

• A rock is not a mineral, and minerals do not always make rocks
• Most rocks are made of minerals, but some rocks have no minerals
• Examples of rocks with minerals: granite, shale, limestone, marble, sandstone, coal
• Examples of rocks without minerals: peat, chalk, flint

Learn the differences between rocks and minerals, including their definitions and characteristics. Discover what makes a mineral and how it's distinct from a rock.