Download File - Wines Science Jeopardy 2013

Rocks and Minerals
Earth’s crust is made of rock, and rock is made of natural substances called MINERALS. There are three main types
of rock—sedimentary, igneous, and metamorphic rock. Each type is produced in different ways. The oldest rocks on
Earth were formed about 3.8 billion years ago.
THE ROCK CYCLE
The rocks that form Earth’s crust are continually destroyed and remade in an endless process called the rock cycle.
Rock is formed by melting; by cooling and solidifying; by changing through heat and pressure; by weathering and
erosion; and by compression and cementation.
WHAT ARE IGNEOUS ROCKS?
Igneous rocks form when magma (molten rock) rises from deep underground and cools and solidifies at or near
Earth’s surface. Igneous rock that forms under the ground may later reach the surface because of geological
upheaval. It may also be exposed as the rocks above are worn away. Igneous or volcanic rock includes granite and
basalt.
WHAT ARE SEDIMENTARY ROCKS MADE OF?
Sedimentary rocks are made of fine rock particles that have been worn away and then carried by rivers, glaciers, or
the wind and collect in lakes and oceans. The tiny fragments are then compressed (squashed) and cemented together
to form sedimentary rock in a process called lithification.
HOW ARE METAMORPHIC ROCKS CREATED?
Metamorphic rocks are formed when existing rocks are changed underground by great heat or pressure, or both.
When volcanoes erupt and when mountains are formed by the movement of Earth’s tectonic plates, rocks are heated
and squeezed. The minerals in the rocks are then changed, forming metamorphic rocks.
MINERALS
Rocks are made of natural, nonliving chemical substances called minerals. Some rocks contain only one mineral.
For example, marble is made of the white mineral calcite. Most rocks, however, containCRYSTALS of several
different minerals.
WHAT ARE THE MOST VALUABLE MINERALS?
Some of the most valuable minerals are ores— minerals that contain metals such as gold, iron, and aluminum. Of
these, gold is the most precious because it is soft and easy to work and does not tarnish. Other minerals are prized as
GEMSTONES. Fossil fuels, such as coal, produce energy. Minerals such as sulfur and mica are used in industry.
Granite and sandstone are used as building stones.
CRYSTALS
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Crystals are solid, regular, geometric shapes formed by most minerals. They have smooth surfaces (called faces),
straight edges, and symmetrical corners because they are built up from a regular framework of atoms (tiny particles)
called a lattice.
HOW DO CRYSTALS FORM?
Crystals form as a molten solid (such as molten rock) cools, or as liquid evaporates (turns into water vapor) from a
solution that contains a dissolved mineral. A crystal grows as more and more atoms attach to the basic lattice. Slowgrowing crystals are larger than those that form quickly.
GEMSTONES
About 50 of the 3,000 minerals found on Earth are prized as gemstones. Although they may not shine in their natural
state, they can be cut and polished to form sparkling stones. Diamonds, the hardest minerals on Earth, are made of
pure, crystallized carbon and are among the world’s most prized gemstones.
WHERE ARE GEMSTONES FOUND?
Many gemstones are found in mountainous regions, usually in rocks that have been subjected to great heat or
pressure. They are also found in the sediment on lake and river beds. Diamonds are often mined from rocks found
deep underground.
Properties of Minerals
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Color – this varies depending on the chemicals present and is the least informative
in identifying a mineral variety
Luster – what the surface looks like in the light
Specific Gravity – how heavy it feels, heft
Crystal Form – shape of crystal, shape the mineral would take if it room to grow in
a cavity, not massive – some minerals have a number of different crystal shapes
Cleavage – pattern when mineral is broken – in planes or conchoidal-cleavage is
when a mineral breaks with smooth flat surfaces. Cleavage can be described as
perfect, good, imperfect, poor.
Fracture
Tenacity - toughness, how cohesive the mineral is, if it falls apart
Hardness – what it can scratch & what scratches it
Transparency - The ability to transmit light. Depending on a number of things,
rocks & minerals can also transmit light. Many rocks that are opaque when in a
chunk, are translucent when cut into very thin slices.
Gems stones are often valued on how clear, or transparent they are.
Special Properties– magnetism, chatoyancy, fluorescence, odor, streak, burn test,
conductivity
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