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

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Handleiding

The geode takes

shape

YOU WILL NEED

› Plastic geode mold

› Plaster gypsum

› Wooden spatula

› Large measuring cup

› Measuring spoon

› Alum seed crystals

from Experiments

 and 

› Sandpaper

› All-purpose glue

› Empty yogurt cup

› Black ink or watercolor paint

HERE’S HOW

1. Cover your work surface with old

newspapers. Pour 75 ml of cold water into

the empty yogurt container.

2. Fill the large measuring cup with gypsum,

and mix it with the water; stir thoroughly

with the wooden spatula, until there are no

more clumps of gypsum.

3. Pour the plaster mixture into the molds.

Spread the mixture up along the walls to

create a cavity in the middle. This will be

easy as long as the mixture is thick enough.

The walls of the geode shouldn’t be too

thin, or the geode will break after it

hardens. The upper edge in particular has to

be at least 5 mm (0.2 in) thick, because you

will be setting the other half on it later on.

4. Before the plaster has hardened, sprinkle

half of the seed crystals that you already

grew into various locations in the hollow

area of your geode half, and press them

lightly into the plaster. Repeat steps 1

through 4 to make the second geode half.

5. Let the geode halves dry for a whole day.

6. Carefully remove the geodes halves from

their molds.

1 2 3

4 5

6 7

8 9

Caution: Plaster can

cause dust. Do not

inhale dust or powder.

Do not place the

materials in the

mouth. Do not apply

to the body. Wash

hands after use.

Follow the safety

information on page 6

before and during use.

TIP !

If you want the

geode to be dark

gray on the

outside, add a few

drops of ink or

black watercolor

paint to the water.

7. Smooth the edges of the geode halves with the

sandpaper, and check to see that their edges

line up by setting them against each other.

8. Use the measuring spoon to scrape two small

holes in one geode half, spaced about 2 cm (1

in) apart. The hole diameter should be just

large enough for the thin pipette tube to fit

into it. You will later add the crystal growing

solution through these holes.

9. Glue together the two halves with the all-purpose glue, leaving the

holes unobstructed. Let the geode dry well. To make the joint

between the two halves as unnoticeable as possible, you can smooth

it a little more with the sandpaper, or spread more plaster on it.

75 ml



Homemade Crystals

EXPERIMENT 7

TIP !

Read the instructions through carefully first, get

everything ready, and be speedy while you work,

because otherwise the plaster will harden too quickly.

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