Earth Materials Lecture 2: Physical properties of Minerals Part 2

Question 1

Define hardness

Answer 1

Resistance to scratching

Question 2

What is the scale of hardness?

Answer 2

Freidrich Mohs scale of hardness (1812).

Arbitrary scale of 1 to 10.

Question 3

What is one method/test to see how Minerals react to acids?

Answer 3

Cold, dilute HCI

For example of Calcite and dolomite.

Question 5

What is the specific gravity of a mineral?

Answer 5

The ratio of weight of mineral in relation to water.

Some minerals can be very heavy/dense.

Question 6

Define polymorphism

Answer 6

Polymorphs or polymorphism are minerals that have the same chemical formula however have a different atomic structure. E.g. Pyrite and Marcasite

Question 7

Define an allatrope

Answer 7

Allatropes are the various physical forms an element can take.

For example, Allatropes of Carbon are diamond, graphite, graphene and buckminsterfullerene.

Question 8

Define a pseudomorph

Answer 8

When one mineral replaces another but retains the chemical stucture.

Question 9

Define an Isomorph

Answer 9

When a mineral has the same atomic structure as another.

Question 10

Define the Diaphaneity

Answer 10

The ability of a mineral to transmit light.
Transparent, translucent or opaque

Question 11

Define the lustre

Answer 11

The ability of a mineral to reflect light.
Does depend on the cleanliness of the mineral

Question 12

Define iridescence

Answer 12

The internal diffraction and reflection of light

Question 13

Define mineral tarnish

Answer 13

Surface iridescence

Question 14

Define chatoyancy

Answer 14

band of light at right angles to
length of (fibrous) crystals.

Question 15

What are fluorescent and phosphorescent minerals

Answer 15

Minerals that are fluorescent/glow

Question 16

Define the coordination number

Answer 16

The number of atoms or groups
surrounding a given atom.

The atoms surrounding one atom in a three dimensional lattice.

E.g. 8 coordination number, 8 cubic structure.

Question 17

Define and explain a solid solution mineral

Answer 17

A solid solution mineral is a mineral which rather than being a single chemical composition, is a homogenous mixture of two substances which have a similar size and charge of their ions. These solid solution mixtures are portrayed in a percentage ,for example 10% forsterite 90% iron = forsterite)

Question 18

What is the process which allows solid solution minerals to exist?

Answer 18

Ionic substitution

Question 19

Explain ionic substitution

Answer 19

Ionic substitution is when elements with ions of a similar charge and size can replace existing ions in a mineral lattice.

The more ionic substitution that happens