Thames & Kosmos Kids First: Crystals, Rocks & Minerals handleiding

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Handleiding

WHAT’S HAPPENING

The streak color is the color of the fine

powder residue of the mineral that rubs

off on the porcelain.

• Colorless minerals White (and

thus barely visible) streak

• Yellow-shining pyrite Greenish

black streak

• Hematite Reddish brown streak

• Bornite Greenish black streak

• Magnetite

Black streak

The experiment clearly shows that

the streak color isn’t always the same

as the color of the actual mineral.

Color and streak

YOU WILL NEED

› Mineral specimens

› Magnifying lens

› Cup or plate made of light-colored ceramic or

porcelain with an unglazed (rough) area.

HERE’S HOW

. Porcelain dishware is usually glazed and

therefore smooth. But on the underside it

has a rough, unfinished, unglazed area. You

will use this area to determine the streak

color. Vigorously rub each of the minerals

across a fresh spot of unglazed porcelain.

Use the magnifying lens to investigate the

colors of the resulting streaks.



ABOUT

SOAPSTONE

Hardness Density

1 2.7

This soft, greasy-

feeling, water-

repellent mineral

contains the

elements

magnesium, silicon,

and oxygen, and has

been used for

centuries in

sculptures and

carved works of art.

Today it has many

industrial uses

including as a gentle

water-repellent

abrasive, with harder

types used as a

material in oven

manufacturing

because they hold

heat well.

ABOUT

HEMATITE

This black compound of iron and oxygen is

one of the earliest iron ores to be used by

humans. Even Stone Age people used

reddish colored ground hematite powder

in their cave paintings. This mineral is also

the source of the red coloration of many

rocks, such as red sandstone. Polished

hematite is used as a gemstone.

ABOUT

QUARTZ CRYSTAL

Quartz is one of the most common materials in Earth’s crust, and

it is a component of many rocks. Even sand is composed mostly

of grains of quartz. Quartz has many uses — in manufacturing

the computer chip material silicon, in glass and porcelain

production — and its hardness makes it a useful abrasive. In

addition, many gemstones consist of quartz of various colors,

such as amethyst (purple), citrine (yellow), rose quartz (pink),

agate (multiple stripes), and jasper (blood red).

Hardness Density

5-6 5

Hardness Density

7 2.6

EXPERIMENT 10

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