Geol 101 Lab Exam Review: Minerals

1. What mineral is this?

Quartz: Hardness 7
Conchoidal Fracture
Varieties: Crystal, Smokey, Rose

Calcite: Hardness 3, Rhombohedral Cleavage, Varieties: Iceland Spar, Optical Calcite

Topaz: Hardness 8, Cleavage, Varieties: Blue, Yellow, Pink

Feldspar: Hardness 6, Two directions of Cleavage at nearly right angles, Varieties: Orthoclase, Plagioclase

Quartz is known for its hardness, conchoidal fracture, and various varieties like crystal, smokey, and rose. Topaz, Calcite, and Feldspar possess different characteristics such as differing hardness levels, cleavage properties, and distinct varieties, making them incorrect answers in this context.

Explanation

Quartz is known for its hardness, conchoidal fracture, and various varieties like crystal, smokey, and rose. Topaz, Calcite, and Feldspar possess different characteristics such as differing hardness levels, cleavage properties, and distinct varieties, making them incorrect answers in this context.

2. What mineral is this?

Galena:
3 cleavages (Cubic Cleavage)
Very Heavy

Pyrite: Gold color, brittle, brassy luster.

Quartz:6 cleavages (Conchoidal Cleavage)Moderate weight.

Hematite: Metallic luster, reddish-brown streak.

The correct answer, Galena, is known for its cubic cleavage and being very heavy. The incorrect answers provided describe different minerals with distinct characteristics and properties that differentiate them from Galena.

Explanation

The correct answer, Galena, is known for its cubic cleavage and being very heavy. The incorrect answers provided describe different minerals with distinct characteristics and properties that differentiate them from Galena.

3. What mineral is often referred to as 'Fool's Gold' and has a black streak and cubic crystal form?

Quartz

Pyrite ("Fools Gold")
Black Streak
Cubic Crystal Form

Hematite

Gold

Pyrite is commonly known as 'Fool's Gold' due to its metallic luster and pale brass-yellow hue. It has a black streak when scratched across a surface and typically forms cubic crystals.

Explanation

Pyrite is commonly known as 'Fool's Gold' due to its metallic luster and pale brass-yellow hue. It has a black streak when scratched across a surface and typically forms cubic crystals.

4. What mineral is this?

Quartz - Hard and glassy mineral

Feldspar - Common in igneous rocks

Calcite - Reacts with weak acid like vinegar

Muscovite "Micah"
Flakey/Platey
Very soft (Scratch with fingernail)

Muscovite is characterized by its flakey/platey structure and softness, making it easy to scratch with a fingernail.

Explanation

Muscovite is characterized by its flakey/platey structure and softness, making it easy to scratch with a fingernail.

5. What mineral is this?

Calcite Fizzes w/ acid

Quartz Hard (Scratch glass)

Feldspar Forms in a cubic shape

Biotite "Micah"
Flakey/Platey
Very Soft (Scratch w/ fingernail)

The correct answer is Biotite 'Micah' which is flakey/platey and very soft, being scratchable with a fingernail. Quartz is hard and can scratch glass, Calcite fizzes when exposed to acid, and Feldspar forms in a cubic shape.

Explanation

The correct answer is Biotite 'Micah' which is flakey/platey and very soft, being scratchable with a fingernail. Quartz is hard and can scratch glass, Calcite fizzes when exposed to acid, and Feldspar forms in a cubic shape.

6. What mineral is described by the following characteristics: Na-Plagioclase, 2 cleavages at almost 90 degrees, lighter color, and striations on cleavage faces?

Muscovite

Pyroxene

Na-Plagioclase
2 cleavages at almost 90 deg
Lighter Color
Striations on cleavage faces

Quartz

The characteristics mentioned point towards Na-Plagioclase, specifically the cleavages at almost 90 degrees and the striations on cleavage faces.

Explanation

The characteristics mentioned point towards Na-Plagioclase, specifically the cleavages at almost 90 degrees and the striations on cleavage faces.

7. What mineral is this?

Quartz3 cleavagesDiamond-shaped faces at intersecting 60 and 120 deg.

Calcite3 cleavagesRhombic cleavageLess than 90 deg angle between cleavages.

Pyrite3 cleavagesCubic crystalsGolden metallic luster.

Ca-Plagioclase
2 cleavages at almost 90 deg
Darker color
Striations on cleavage faces

The correct answer describes the characteristics of Ca-Plagioclase, including its cleavages at almost 90 degrees, darker color, and striations on cleavage faces. The three incorrect answers provide details about Quartz, Calcite, and Pyrite, which have distinct properties that differentiate them from Ca-Plagioclase.

Explanation

The correct answer describes the characteristics of Ca-Plagioclase, including its cleavages at almost 90 degrees, darker color, and striations on cleavage faces. The three incorrect answers provide details about Quartz, Calcite, and Pyrite, which have distinct properties that differentiate them from Ca-Plagioclase.

8. What mineral is this?

PyriteMetallicGold Streak

Magnetite
Magnetic
Black Streak

HematiteReddish-Brown Streak

QuartzGlassyWhite Streak

The correct mineral is Magnetite as it exhibits magnetic properties and leaves a black streak when scratched against a surface.

Explanation

The correct mineral is Magnetite as it exhibits magnetic properties and leaves a black streak when scratched against a surface.