Agate facts for kids
Quick facts for kids Agate |
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Moss agate pebble, 2.5 cm (1 inch) long
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| General | |
| Category | Quartz variety |
| Formula (repeating unit) |
Silica, SiO2 |
| Identification | |
| Color | White to grey, light blue, orange to red, black |
| Crystal habit | Cryptocrystalline silica |
| Crystal system | Rhombohedral Microcrystalline |
| Cleavage | None |
| Fracture | Conchoidal with very sharp edges |
| Mohs scale hardness | 7 |
| Luster | Waxy |
| Streak | White |
| Specific gravity | 2.58-2.64 |
| Refractive index | 1.530-1.540 |
| Birefringence | up to +0.004 (B-G) |
| Pleochroism | Absent |
Agate is a beautiful type of quartz and a mineral. It comes in many different colors and patterns. You can often find agate inside large rocks like boulders. It takes a very long time for agates to form, sometimes as long as 50 million years!
Agate is known for its cool colored bands or stripes. Sometimes, you might even find Amethyst or other Quartz crystals growing inside larger agate pieces. People have used agate for a long time in hardstone carving. Ancient cultures, like the Minoans on Crete during the Bronze Age, used agate for art and tools.
Contents
What is Agate?
How Agate Got its Name
The name "agate" comes from a Greek philosopher and naturalist named Theophrastus. He found this stone along the shore of the Achates River in Sicily. This happened a very long time ago, between the 4th and 3rd centuries BC. Today, that river is called the Dirillo River.
How Agate Forms
Most agates form inside volcanic rocks or old lava flows. They often look like rounded lumps called nodules. Agate can also fill cracks or veins in these rocks.
When you cut an agate in half, you can often see many thin, parallel lines. These lines create a striped look. This type of agate is known as banded agate or striped agate.
Many agates are actually hollow inside. This happens when the mineral layers don't completely fill the space. The inside of these hollow agates often has tiny quartz crystals. Sometimes, these crystals are amethyst (purple quartz). These crystal-lined hollow rocks are called geodes.
Agates are very strong and don't wear away easily. This is why you can find them as pebbles in the soil, in streams, or along beaches.
Uses of Agate
Agate in Art and Jewelry
Agate has been used for centuries to make beautiful decorative items. Artists use it for things like pins, brooches, and other types of jewellery. It's also used for paper knives, inkstands, and marbles.
You can still see agate used for decoration today. For example, a church in Yachats, Oregon, has windows made from agate pieces found on local beaches.
Agate in Industry
Agate is very hard and can be polished to a smooth, shiny surface. It also resists damage from chemicals. Because of these qualities, agate is used in some special tools. It has been used to make very precise parts for laboratory balances. It is also used for mortars and pestles, which are tools for crushing and mixing chemicals.
Images for kids
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Botswana agate
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Hollow agate
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Agate drinking horn, Tang dynasty
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Agatized coral
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Dendritic agate
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"Turritella agate" (Elimia tenera)
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Crazy lace agate
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A 6.8 kg (15 lb) barrel full of tumble-polished agate and jasper
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Zegelring in goud met intaglio met portret of Commodus in nicolo, 180 to 200 NC, vindplaats- Tongeren, de Schaetzengaarde 22, 1998, losse vondst (mogelijk goudschat), collectie Gallo-Romeins Museum Tongeren, GRM 1892.jpg
Gold Roman signet ring with portrait of emperor Commodus in niccolo agate, 180-200 CE, found in Tongeren, Gallo-Roman Museum (Tongeren)
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The "Rubens Vase" (Byzantine Empire). Carved in high relief from a single piece of agate, most likely created in an imperial workshop for a Byzantine emperor.
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Victorian banded agate earrings
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See also
In Spanish: Ágata (mineral) para niños
