Rocks and Minerals — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Which rock type is most likely to contain fossils?
A) igneous
B) sedimentary
C) metamorphic
D) all types equally
Fossils form in sedimentary rocks when organisms are buried in sediment. The heat and pressure that form igneous and metamorphic rocks would destroy organic remains.
2. What happens to sedimentary rock when it is exposed to extreme heat and pressure?
A) It melts into lava
B) It becomes metamorphic rock
C) It turns into igneous rock
D) It breaks into sediment
When sedimentary rock is subjected to intense heat and pressure (usually from burial or tectonic forces), it metamorphoses into metamorphic rock.
3. A student finds a rock with visible layers of different colored sand pressed together. What type of rock is it most likely?
A) igneous
B) sedimentary
C) metamorphic
D) mineral
Visible layers of compressed sediment (sand) are a characteristic feature of sedimentary rocks like sandstone.
4. Which mineral property is measured by scratching one mineral against another?
A) luster
B) streak
C) hardness
D) color
Hardness is tested by attempting to scratch a mineral with another mineral or object of known hardness (Mohs scale).
Part B: Fill in the Blank
Write the correct answer on each line.
1. When magma cools slowly underground, it forms igneous rocks with large crystals.
Slow cooling allows mineral crystals more time to grow larger. Granite is an example with visible large crystals.
2. The three rock types in the rock cycle are igneous, sedimentary, and metamorphic.
The rock cycle connects all three rock types: igneous, sedimentary, and metamorphic — each can transform into the others.
3. Weathering and erosion break rocks into small pieces called sediment.
Weathering breaks rocks apart; erosion carries the pieces away. The small particles deposited are called sediment.
4. Quartzite is a metamorphic rock that forms from sandstone.
Sandstone (sedimentary, made of quartz sand) becomes quartzite when subjected to metamorphic heat and pressure.
5. A mineral that has a metallic luster looks like polished metal.
Metallic luster minerals (like pyrite, galena, gold) reflect light like polished metals — shiny and opaque.