Most of the Earth is composed of rocks. Rock outcrops
form some of our planet’s most spectacular scenery:
white chalk cliffs, pink sandstone arches, and the grey
granite of Yosemite Valley. Rocks, in turn, are composed
of minerals (Fig. 1–2). Although more than 3500 different
minerals exist, fewer than a dozen are common.
Geologists study the origins, properties, and compositions
of both rocks and minerals.
Geologists also explore the Earth for the resources
needed in our technological world: fossil fuels such as
coal, petroleum, and natural gas; mineral resources such
as metals; sand and gravel; and fertilizers. Some search
for water in reservoirs beneath Earth’s surface.
Most of the Earth is composed of rocks. Rock outcropsform some of our planet’s most spectacular scenery:white chalk cliffs, pink sandstone arches, and the greygranite of Yosemite Valley. Rocks, in turn, are composedof minerals (Fig. 1–2). Although more than 3500 differentminerals exist, fewer than a dozen are common.Geologists study the origins, properties, and compositionsof both rocks and minerals.Geologists also explore the Earth for the resourcesneeded in our technological world: fossil fuels such ascoal, petroleum, and natural gas; mineral resources suchas metals; sand and gravel; and fertilizers. Some searchfor water in reservoirs beneath Earth’s surface.
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