Mineral — Science definition

A naturally occurring, inorganic solid with a definite chemical composition and an orderly, repeating crystal structure.

Where it is taught

In use

Not every hard, shiny rock you pick up is a mineral — to earn that name, a substance has to pass a strict five-part test.

Minerals & Their Properties

Questions using mineral

Problem 1

Which of these is NOT one of the five traits required for a substance to be classified as a mineral?
  1. Naturally occurring
  2. Made of living tissue
  3. A solid
  4. Definite chemical composition
Answer and explanation

Made of living tissue

Minerals must be inorganic — not created by living organisms; the other three are indeed required traits.

Problem 2

Which property is generally the LEAST reliable for identifying a mineral?
  1. Streak
  2. Color
  3. Hardness
  4. Luster
Answer and explanation

Color

Color is unreliable because trace impurities can cause the same mineral to appear in several different colors.

Problem 3

A mineral breaks apart along smooth, flat surfaces that follow its internal crystal structure. This property is called…
  1. fracture
  2. cleavage
  3. luster
  4. streak
Answer and explanation

cleavage

Breaking along smooth, flat planes that follow the crystal structure is cleavage; uneven, rough breakage is called fracture.

Problem 4

A specimen has mass 54 g and displaces water from 20 to 38 mL when fully immersed without bubbles. Find its density and explain what additional evidence is needed to identify its mineral.
Answer and explanation

Volume is 18 mL = 18 cm³, so density is 54/18 = 3 g/cm³. Use hardness, streak, cleavage and other characteristic observations; density alone may match several candidates.

Find displaced volume: 38−20 = 18 cm³.

Calculate density: 54/18 = 3 g/cm³.

Compare several tests and uncertainty rather than naming a mineral from one value.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

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