Lab 1:

Lab 3: Mineral Properties, Uses, and Identification

Introduction:

Minerals: inorganic, naturally occurring substances that have a characteristic chemical

composition, distinctive physical properties and crystalline structure.

Crystalline structure: orderly three-dimensional arrangement of atoms or molecules, and

materials with crystalline structure form crystals

Rocks: aggregates of one or more minerals

Eight rock forming minerals: quartz, muscovite, biotite, plagioclase feldspar, olivine,

potassium feldspar, pyroxene/augite, amphibole/hornblende

3A: Mineral Properties and Uses

Color: useful in identifying minerals in rocks.

Clarity: transparent, translucent or opaque.

Streak: color of substance once ground to a fine powder (demonstrate)

Luster: how a mineral’s surface reflects light. Metallic or Non-Metallic (not just shiny)

Hardness: Mohs Scale of Hardness (pp 53) – Imp: is the mineral scratching the object or

vice versa (demonstrate)

Crystal form: external feature of mineral crystals – only form when growth is unrestricted

Cleavage or fracture: sets of parallel surfaces of weak chemical bonding: excellent, good,

poor or absent (pp 56) – Imp: different from crystal form

Reaction to HCl: 10% HCl soln to test for presence of calcium carbonate (demonstrate)

Striations v. exsolution lamellae: striations are straight hairline grooves on the cleavage

surface, exsolution lamellae are thin, discontinuous, subparallel lamellae (thin discontinuous layers) of plagioclase (potassium feldspars only)

Magnetic properties: magnetite is magnetic

Specific gravity: ratio between the density of a substance and the density of water –

unitless number the same as the density of that object

Taste and smell: sulfur, halite (table salt) have distinct flavors and smells (don’t do this at

home), can be an easy way to identify samples

3B: Mineral Identification and Appreciation

Go through two examples with overhead sheets

3C: Mineral Resources and Commodities

Minerals are used every day: