Earth's Jewels
What do we call an inorganic, solid material found in nature that always has the same chemical makeup, atoms arranged in an orderly pattern, and properties such as cleavage and fracture, color, hardness, and streak and luster? (p.256)
Mineral.
Each mineral has unique characteristics that can be used to identify it. So far, more than 4,000 minerals have been identified.
One clue into a mineral's identity is the way it breaks. What property is demonstrated by a mineral that splits into pieces with smooth, regular planes that reflect light? (p.258)
Cleavage.
For example, the mineral mica splits into thin sheets.
What do we call intrusive or extrusive rock that is produced when melted rock from inside Earth cools and hardens? (p.265)
Igneous Rock.
The deeper you go into the interior of Earth, the higher the temperature is and the greater the pressure is.
What do we call sedimentary rocks that are made of grains of minerals or other rocks that have moved and been deposited in layers by water, ice, gravity or wind? (p.269)
Detrital rocks.
Other minerals dissolved in water act to cement these particles together.
What do we call the diagram that shows the slow, continuous process of rocks changing from one type to another? (p.275)
The rock cycle.
The rock cycle shows how rocks are recycled constantly from one kind of rock into another. In other words, the rock cycle is always happening!
What do we call a solid inorganic material that is usually made of two or more minerals and can be metamorphic, sedimentary, or igneous (p.256)
Rocks.
Fracture.
Quartz and flint break apart in uneven, jagged pieces.
What word describes igneous rocks that have small or no crystals and form when melted rock cools quickly on Earth's surface? (p.265)
Extrusive.
Extrusive igneous rocks can form in two ways. First, volcanoes can erupt and shoot out lava and ash. Second, lava may ooze out of the ground or into water from a fissure. Lava cools quickly before large mineral crystals have time to form.
To identify detrital sedimentary rock, you use the size of the grains that make up the rock. What do we call the type of detrital rock that is made up of pebbles mixed and cemented together with other sediment? (p.270)
Conglomerates.
What word describes metamorphic rocks with visible layers of minerals? (p.274)
Foliated.
The term "foliated" means "leafy." These minerals have been heated and squeezed into parallel layers, or leaves.
What do we call a solid material with atoms arranged in a repeating pattern? (p.258)
Crystals.
What property is demonstrated by scraping a mineral across an unglazed, white tile, and observing the color of the powdered mineral? (p.259)
Streak.
The streak of a mineral is not necessarily the same color as the mineral itself. While gold and pyrite (aka, fool's gold) both are yellowish in color, gold has a yellow streak, but pyrite makes a greenish-black or brownish-black streak.
What word describes a type of igneous rock that generally contains large crystals and forms when magma cools slowly beneath Earth's surface? (p.265)
Intrusive.
Intrusive igneous rocks form when a huge glob of magma from inside Earth is forced upward toward the surface, but never reaches it.
What type of sedimentary rock forms when seawater, loaded with dissolved minerals, evaporates? (p.270)
Chemical sedimentary rocks.
Chemical rocks can also form when mineral-rich water from geysers, hot springs, or salty lakes evaporates.
What word describes metamorphic rocks that lack distinct layers or bands? (p.274)
Nonfoliated.
If the mineral grains are visible at all, they do not seem to line up in any particular direction.
What do we call a rare, valuable mineral that can be cut and polished? (p.262)
Gems.
Cutting and polishing gems gives them a beautiful appearance, and makes them ideal for jewelry.
Luster.
If it shines like a metal, it has a metallic luster. Nonmetallic minerals can be described as having a pearly, glassy, dull, or earthy luster.
What type of rock is made from pieces of other rocks, dissolved minerals, or plant and animal matter that collect to form rock layers? (p.269)
Sedimentary rocks.
Rivers, ocean waves, mudslides, glaciers and even wind can carry sediment. When sediment is dropped, it collects in layers. Most sedimentary rock takes thousands to millions of years to form.
What type of sedimentary rock forms over millions of years as living matter dies, piles up, and then is compressed into rock? (p.270)
What processes could cause an igneous rock to become sediment, and then later sedimentary rock? (p.275)
Igneous rock becomes sediment through weathering and erosion.
Sediment becomes sedimentary rock through compaction and cementation.
What do we call a material that contains enough of a useful metal that it can be mined and sold at a profit? (p.263)
Ore.
Many metals that humans use come from ores. For example, the iron used to make steel comes from the mineral hematite, lead for batteries is produced from galena, and the magnesium used in vitamins comes from dolomite.
What property compares the weight of a mineral with the weight of an equal volume of water? (p.260)
Specific gravity.
Some minerals are heavier for their size than others. Pyrite is about 5 times heavier than water. Pure gold is about 19 times heavier than water.
What type of rock forms when existing rock is heated or squeezed? (p.273)
Metamorphic rock.
The word "metamorphic" means "change of form."
What is the special term for a type of organic rock that is the remains or trace of a once-living plant or animal? It could be a bone, or even a footprint. (p.271)
Fossils.
Limestone contains many small fossils!
What process(es) could turn igneous rock into metamorphic rock? (p.275)
Igneous rock is subjected to heat and pressure or melting and turns into metamorphic rock.