Minerals & Their Properties — Drills · Grade 9 Science

Chapter: Rocks, Landscapes & Water

What these drills covers

By the end of Minerals & Their Properties you should be able to:

8 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: mineral, luster, streak, hardness.

Problem 1

A mineral must be
  1. naturally occurring, inorganic, solid, with a definite composition and ordered structure
  2. any solid found in the ground
  3. any crystal, natural or made
  4. organic in origin
Answer and explanation

naturally occurring, inorganic, solid, with a definite composition and ordered structure

All five conditions are part of the definition.

Problem 2

Hardness in minerals is usually compared using
  1. the Mohs scale
  2. the Richter scale
  3. the pH scale
  4. density alone
Answer and explanation

the Mohs scale

Mohs ranks minerals by which scratches which, from talc to diamond.

Problem 3

Streak is
  1. the colour of the mineral's powder
  2. the shine of the surface
  3. the shape of the crystal
  4. its density
Answer and explanation

the colour of the mineral's powder

Streak is often more reliable than surface colour because it does not vary with impurities.

Problem 4

Why is colour a poor identifier for many minerals?
  1. It cannot be seen
  2. Small impurities change it while the mineral stays the same
  3. All minerals are grey
  4. Colour changes daily
Answer and explanation

Small impurities change it while the mineral stays the same

Quartz occurs in many colours; streak, hardness and cleavage are steadier.

Problem 5

Cleavage describes how a mineral
  1. breaks along flat planes related to its structure
  2. reflects light
  3. dissolves
  4. forms
Answer and explanation

breaks along flat planes related to its structure

Cleavage reflects planes of weaker bonding in the crystal structure.

Problem 6

A mineral sample has mass 156 g and volume 60 cm³. What is its density in g/cm³, to one decimal place?
Answer and explanation

2.6 g/cm³

156/60 = 2.6 g/cm³, consistent with quartz or feldspar.

Problem 7

Explain why several tests are used together to identify a mineral.
Answer and explanation

No single property is unique to one mineral: many share a colour, a hardness or a density. Combining tests narrows the possibilities, because the chance of two minerals matching on streak, hardness, cleavage and density together is small. Using one test alone invites a confident wrong identification.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Is ice a mineral? Justify your answer against the definition.
Answer and explanation

Naturally formed ice meets the definition: it occurs naturally, is inorganic, is solid at its formation temperature, has the definite composition H₂O, and has an ordered crystal structure. Ice made in a freezer fails the 'naturally occurring' condition. The case is useful because it shows the definition has to be applied condition by condition rather than by intuition.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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