Earth Science 205 Chapter 3 Quiz

Mineral Identification

• Salt (NaCl) is classified as a mineral, while amber is organic, and saltwater and oil are not solid minerals.
• Glass lacks a crystal structure, disqualifying it as a mineral despite being an inorganic solid.
• Diffusion refers to the movement of atoms or molecules through a material, relevant in mineral formation alongside precipitation and solidification.

Mineral Formation Methods

• Biomineralization is exemplified by clamshell calcite, formed biologically by organisms.
• Minerals can form through solidification from a melt, precipitation from solution, and solid-state diffusion.

Crystal Characteristics

• Euhedral crystals grow uninterrupted, while anhedral crystals are restricted by space.
• Crystal habit describes the specific shape or arrangement of a cluster of well-formed crystals.
• The streak test reveals the color of a mineral when powdered, which can differ from the mineral's external color.

Hardness and Abundance

• Gypsum is softer than fluorite, according to the Mohs hardness scale, which ranks materials based on scratch resistance.
• Silicates are the most abundant mineral group in the Earth's crust and mantle.

Cleavage and Breakage

• Calcite has three planes of cleavage, with distinct geometrical arrangements.
• Conchoidal fracture describes a smooth, curved break typical in minerals like quartz.

Diamonds and Metamorphic Rocks

• Diamonds form under high pressure from carbon at depths of 100 km or more, distinct from biomineralized or precipitated minerals.
• Metamorphic rocks arise from existing rocks subjected to high temperatures and pressures, without melting, leading to changes in mineralogy and texture.

Rock Classification

• Crystalline rocks feature interlocking minerals and can be igneous, sedimentary, or metamorphic in origin.
• Bricks are human-made products and therefore do not qualify as rocks.

Pyrite Characteristics

• Pyrite exhibits a metallic luster and cubic crystal habit, observable through visual inspection.

Field Study Tools

• A magnifying glass (hand lens) is most practical for studying rocks in the field, while more complex equipment is used in laboratory settings.

Sedimentary Rock Formation

• Sedimentary rocks form at or near the Earth’s surface through cementing rock grains or precipitation from water, differentiating them from igneous and metamorphic rocks.

Gemstone Hardness

• Amethyst, topaz, diamond, and sapphire are all harder than glass, indicating their resilience and value as gemstones.

Cleavage in Minerals

• Minerals that cleave into thin sheets have one plane of cleavage, allowing for flat, sheet-like separation similar to stacked papers.