Mineral Lab 1

Question 1

Mineral

Answer 1

A naturally occurring substance that is solid and inorganic representable by a chemical formula, and has an ordered atomic structure, there are over 4,900 mineral species

Question 2

Rock

Answer 2

Can be an aggregate of minerals or non-minerals, does not have a specific composition

Question 3

Color

Answer 3

Most obvious property, but often non-diagnostic. Cased by electromagnetic radiation interacting with electrons
Malachite - green, azurite - blue

Question 4

Streak

Answer 4

The color of a mineral in powdered form. Streak is consistent regardless of mineral color.
Hematite - black, silver, or red mineral with cherry-red to reddish brown streak. Streak is more distinctive for metallic minerals. Those harder than 7 are too hard to produce a streak

Question 5

Luster

Answer 5

How light reflects from the mineral’s surface. Metallic minerals have high reflectivity, ex. pyrite and galena

Question 6

Non-metallic lusters

Answer 6

• Vitreous - a glassy luster common in silicate minerals
• Pearly - such as in talc, resinous, such as members of the garnet group
• Satiny - resembling the luster of satin or silk cloth, common in fibrous minerals such as asbestiform chrysotile
• Earthy - lacking reflection, completely dull like dry soil
• Porcelaneous - resembling the luster of porcelain (translucent white ceramic ware)
• exposed surfaces of most minerals, especially metallic, tarnish to a more dull or earthy luster

Question 7

Hardness, Mohs Hardness Scale

Answer 7

MOHS Hardness Scale
1 - Talc
2 - Gypsum
2 to 2.5 - Fingernail
3 - Calcite
3.5 - Copper coin
4 - Fluorite
5 - Apatite
5 to 5.5 - Glass
5 to 6 - Steel knife
6 - Orthoclase or Fedlspar
6.5 to 7 - Streak plate
7 - Quartz
8 - Topaz or Beryl
9 - Corundum
10 – Diamond

Question 8

Crystal Form or Crystal Habit

Answer 8

Geometric shapes like cubes, pyramids, or prisms. Perfect crystals only form with unrestricted growth, which is rare. Not a good diagnostic.

Question 9

Breakage

Answer 9

Minerals have an atomic arrangement. Weakness in the structure influences how it breaks - cleavage or fracture.

Question 10

Scratch Test

Answer 10

Use common objects such as a streak plate, glass plate, penny and fingernail to make reasonable estimates of a mineral’s hardness. The hardness of a mineral is one of the most important diagnostic properties for mineral identification.

Question 11

Cleavage

Answer 11

When a crystal breaks along planes, typically, in one, two, three, four, or six directions. Not a great diagnostic because not all minerals exhibit cleavage and it can be difficult for non-geologists to identify cleavage. In addition, some minerals exhibit cleavage in some samples but not in others.

Question 12

Fracture

Answer 12

When a mineral is broken in a direction that does not correspond to a plane of cleavage. Types of Fracture:
- Conchoidal fractures are smooth, curved, concave. (Conchoidal fomes from the greek Konchoeides, meaning, “like a mussel”)
- Splintery - breaking into splinters
- Hackly - sharp edges and jagged points
- Fibrous