Earth Materials Lecture 2: Physical properties of Minerals Part 2 Flashcards
Define hardness
Resistance to scratching
What is the scale of hardness?
Freidrich Mohs scale of hardness (1812).
Arbitrary scale of 1 to 10.
What is one method/test to see how Minerals react to acids?
Cold, dilute HCI
For example of Calcite and dolomite.
What is the specific gravity of a mineral?
The ratio of weight of mineral in relation to water.
Some minerals can be very heavy/dense.
Define polymorphism
Polymorphs or polymorphism are minerals that have the same chemical formula however have a different atomic structure. E.g. Pyrite and Marcasite
Define an allatrope
Allatropes are the various physical forms an element can take.
For example, Allatropes of Carbon are diamond, graphite, graphene and buckminsterfullerene.
Define a pseudomorph
When one mineral replaces another but retains the chemical stucture.
Define an Isomorph
When a mineral has the same atomic structure as another.
Define the Diaphaneity
The ability of a mineral to transmit light.
Transparent, translucent or opaque
Define the lustre
The ability of a mineral to reflect light.
Does depend on the cleanliness of the mineral
Define iridescence
The internal diffraction and reflection of light
Define mineral tarnish
Surface iridescence
Define chatoyancy
band of light at right angles to
length of (fibrous) crystals.
What are fluorescent and phosphorescent minerals
Minerals that are fluorescent/glow
Define the coordination number
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.
Define and explain a solid solution mineral
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)
What is the process which allows solid solution minerals to exist?
Ionic substitution
Explain ionic substitution
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
