Unformatted text preview: Introduction to Mineralogy
Introduction to Mineralogy Mineralogy can be: Complex
Interesting Exciting Because… It’s a mix of complex/new ideas, with massive amounts of rote memorization. Objectives
Three parts to class (originally three classes):
Learn chemical properties of minerals 1.
• • Crystallography – spatial arrangement of atoms
Crystal chemistry – what atoms make up minerals and why Analytical methods: 1.
• 1. Physical properties (this week’s lab) – visual observations
Xray diffraction Identify, classify and organize minerals Why study mineralogy?
Why study mineralogy? Minerals are chemical compounds that form from natural chemical/earth processes
Minerals are basic building blocks of rocks
Rocks provide record of earth history and are formed by earth processes
Holistic Earth science: Earth history
Earth processes Definition of Mineral
Definition of Mineral
A naturally occurring, homogeneous solid, with a defined (but generally not fixed) chemical composition and an ordered atomic arrangement 1. Naturally occurring
1. Naturally occurring Why not synthetic (manmade)? E.g. diamonds
Corian countertops (quartz)
Table salt (halite)
Others? Salar de Uyuni, Bolivian Altiplano San Francisco Bay 2. Homogeneous solid
2. Homogeneous solid Minerals can not be PHYSICALLY broken into new compounds How about chemically “broken”?
What would they break into? Why solid? Physical Reaction: Big Feldspar → Little Feldspar
Chemical reaction: Albite → Na+ + Al3+ + SiO44- 3. Defined, but not fixed, 3. Defined, but not fixed, composition The compositions of minerals are strictly defined (stoichiometry), but can vary between compositions
For example: Calcite is CaCO3 but will also contain much Mg, Sr, Fe, Mn etc.
Olivine (Fe,Mg)SiO4 is a group of two main minerals:
Fayalite (Fe2SiO4) Forsterite (Mg SiO )
4 4. Ordered atomic arrangement
4. Ordered atomic arrangement Crystallography – how atoms are arranged in space.
For example: Aragonite (CaCO3) and Calcite (CaCO3) are different minerals but have identical compositions
This is why minerals are referred to by name rather than formula
Mineral names include both composition (chemistry) and crystallography ...
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