formation of minerals

formation from solutions

Most water on Earth, like the water in the oceans, contains elements. The elements are mixed evenly through the water. Water plus other substances makes a solution. The particles are so small that they will not come out when you filter the water. But the elements in water can form solid mineral deposits.

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formation from magma and lava

You are on vacation at the beach. You take your flip-flops off so you can go swimming. The sand is so hot it hurts your feet. You have to run to the water. Now imagine if it were hot enough for the sand to melt. Some places inside Earth are so hot that rock melts. Melted rock inside the Earth is called magma. Magma can be hotter than 1,000C. When magma erupts onto Earths surface, it is known as lava, as Figure 3.17 shows. Minerals form when magma and lava cool.

minerals from salt water

Fresh water contains a small amount of dissolved elements. Salt water contains a lot more dissolved elements. Water can only hold a certain amount of dissolved substances. When the water evaporates, it leaves behind a solid layer of minerals, as Figure 3.18 shows. At this time, the particles come together to form minerals. These solids sink to the bottom. The amount of mineral formed is the same as the amount dissolved in the water. Seawater is salty enough for minerals to precipitate as solids. Some lakes, such as Mono Lake in California, or Utahs Great Salt Lake, can also precipitate salts. Salt easily precipitates out of water, as does calcite, as Figure 3.19 shows. The limestone towers in the figure are made mostly of the mineral calcite. The calcite was deposited in the salty and alkaline water of Mono Lake, in California. Calcium-rich spring water enters the bottom of the lake. The water bubbles up into the alkaline lake. The

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minerals from hot underground water

Underground water can be heated by magma. The hot water moves through cracks below Earths surface. Hot water can hold more dissolved particles than cold water. The hot, salty solution has chemical reactions with the rocks around it. The water picks up more dissolved particles. As it flows through open spaces in rocks, the water deposits solid minerals. When a mineral fills cracks in rocks, the deposits are called veins. Figure 3.20 shows a white quartz vein. When the minerals are deposited in open spaces, large crystals grow. These rocks are called geodes. Figure 3.20 shows a geode that was formed when amethyst crystals grew in an open space in a rock.

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instructional diagrams

No diagram descriptions associated with this lesson

questions

Ways that minerals form include

a. magma cooling.

b. salt water evaporating.

c. dissolved elements precipitating.

-->  d. all of the above

Water plus other substances is a(n)

a. precipitate

b. saline

-->  c. solution

d. geode

Dissolved elements in water can form

a. lava flows.

b. magma pools.

-->  c. mineral deposits.

d. two of the above

Hot fluids

a. flow through open spaces in rocks and deposit solid minerals

b. can hold more dissolved particles than cold fluids

c. can have chemical reactions with rocks

-->  d. all of the above

When water evaporates, any dissolved elements are left behind as mineral deposits. The amount of minerals deposited

a. is the same as the original amount of water.

-->  b. equals the amount of minerals dissolved in the water.

c. is determined by the type of minerals that form.

d. depends on the rate at which the water evaporates.

As the water in a solution evaporates,

a. all dissolved elements evaporate too

b. a chemical reaction occurs to help create minerals

-->  c. it leaves behind a solid layer of minerals

d. nothing happens. Water in a solution cannot evaporate

Underground water is heated by

a. lava

b. dissolved minerals

c. calcite

-->  d. magma

In a water solution, dissolved elements

a. can be filtered out of the water.

b. are mixed evenly throughout the water.

c. may precipitate out of the water.

-->  d. two of the above

Which type of feature may form in open spaces inside rocks?

a. vein

-->  b. geode

c. tufa tower

d. none of the above

Melted rock that erupts on to Earths surface is called

-->  a. lava

b. magma

c. vein

d. melted minerals

Water in rocks underground can be heated by

a. the sun.

-->  b. magma.

c. lava.

d. two of the above

When underground water is heated, it can

a. contain fewer dissolved particles.

-->  b. dissolve more rocks.

c. become a precipitate.

d. all of the above

to come out of a solution as a solid

a. lava

b. geode

c. vein

d. magma

e. solution

-->  f. precipitate

g. rock

water mixed with dissolved substances

a. lava

b. geode

c. vein

d. magma

-->  e. solution

f. precipitate

g. rock

solid mixture of minerals

a. lava

b. geode

c. vein

d. magma

e. solution

f. precipitate

-->  g. rock

Seawater can hold more dissolved minerals than freshwater.

-->  a. true

b. false

melted rock below Earths surface

a. lava

b. geode

c. vein

-->  d. magma

e. solution

f. precipitate

g. rock

Both geodes and veins are mineral deposits in rocks that form from hot solutions.

-->  a. true

b. false

long, narrow mineral deposit

a. lava

b. geode

-->  c. vein

d. magma

e. solution

f. precipitate

g. rock

melted rock that has erupted onto Earths surface

-->  a. lava

b. geode

c. vein

d. magma

e. solution

f. precipitate

g. rock

As water evaporates in a solution, the minerals evaporate too.

a. true

-->  b. false

rock formed by the growth of large mineral crystals

a. lava

-->  b. geode

c. vein

d. magma

e. solution

f. precipitate

g. rock

Underground water that is heated creates magma.

a. true

-->  b. false

Water has the ability to hold dissolved ions.

-->  a. true

b. false

Minerals are used to make many different products.

-->  a. true

b. false

All minerals form in the same way.

a. true

-->  b. false

Some places inside Earth are so hot that underground rocks melt.

-->  a. true

b. false

The only water on Earths surface that contains dissolved salts is the ocean.

a. true

-->  b. false

Salts easily precipitate out of water.

-->  a. true

b. false

The mineral calcite is deposited only when magma cools.

a. true

-->  b. false

Water moves through cracks in rocks below Earths surface.

-->  a. true

b. false

Water can dissolve rocks and form a solution.

-->  a. true

b. false

Geodes result from the formation of large mineral crystals.

-->  a. true

b. false

A vein of minerals forms when lava cools inside a crack in a rock.

a. true

-->  b. false

diagram questions

No diagram questions associated with this lesson