Jasper facts for kids

Quick facts for kids Jasper
Jasper outcrop, Bucegi Mountains, Romania
General
Category	Aggregate rock (impure chalcedony variety)
Formula (repeating unit)	SiO2 (with varying impurities)
Identification
Colour	Most commonly red, but may be yellow, brown, green or (rarely) blue
Crystal habit	Massive
Crystal system	Hexagonal
Cleavage	Indiscernible
Fracture	Conchoidal
Mohs scale hardness	6.5–7
Luster	Vitreous
Diaphaneity	Opaque
Specific gravity	2.5–2.9
Refractive index	1.54–2.65
Birefringence	0.009

Jasper is a beautiful and colorful type of rock. It's made mostly of tiny quartz crystals and other minerals all stuck together. Jasper is usually red, yellow, brown, or green. Sometimes, it can even be blue! The bright red color often comes from tiny bits of iron inside the stone. Jasper is not see-through; it's opaque. When it breaks, it has a smooth surface. People love to use jasper for decorations and as a gemstone. It can be polished to a shiny finish. You might see jasper used in things like fancy vases, seals, or small decorative boxes. This rock is quite dense, weighing about 2.5 to 2.9 grams per cubic centimeter. A special rock called Jaspillite often shows cool bands of jasper within it.

The Story of Jasper's Name and Past

Movable Egyptian ring in green jasper and gold, from 664 to 322 BC or later (Late Period), the Walters Art Museum

Amulet of scarlet jasper, found in Royal Pump Room, Harrogate

Low-relief sphinx pendant made of red jasper, pearl, and enamel, from France, around 1870

The name "jasper" means "spotted or speckled stone." It comes from ancient languages like Greek, Latin, and Old French. People in ancient times loved this stone. Its name can be found in Arabic, Persian, Hebrew, and other old languages.

Ancient Uses of Jasper People have used jasper for thousands of years!

• Around 4,000 to 5,000 BC, green jasper was used to make bow drills in a place called Mehrgarh.
• On the island of Crete, people carved jasper into seals about 1800 BC. These seals were found at the ancient palace of Knossos.
• Ancient people often used jasper that was green. They sometimes compared it to emeralds.
• Some historians believe that red and yellow jasper were used in the High Priest's breastplate mentioned in ancient texts.

Male torso carved from red jasper, from the Bronze Age city of Harappa, Indus Valley civilisation, Pakistan

Archaeologists found a male torso carved from red jasper in Harappa, part of the Indus Valley civilisation from the Bronze Age. This shows how important jasper was for art.

Different Kinds of Jasper

A beautiful vase made from red and yellow jasper, from Germany in the early 1600s. It is now in the British Museum.

A goat-headed basket carved from red jasper, made in Russia in the late 1800s. It is kept in the Kremlin Armoury.

Jasper comes in almost every color! Its color depends on the tiny bits of minerals in the original rock or ash. As the rock forms, it creates amazing patterns. These patterns look like swirls or layers from how the sediment or volcanic ash settled. Scientists believe that hot water moving through the rocks helps jasper form.

Sometimes, minerals spread through cracks in the jasper. This can create patterns that look like tiny plants or trees, called dendritic patterns. The original rock might break or twist. Later, other colorful minerals fill these cracks, making even more unique designs. Over time, the outside of the rock can also develop very bright colors.

Naming different types of jasper can be tricky. Many names come from where the jasper was found. For example, "Bruneau" jasper is named after a canyon. Other names are more imaginative, like "forest fire" or "rainbow" jasper. Some names describe the stone, such as "autumn" or "porcelain" jasper. You might also hear names like "Egyptian brown" or "African red" jasper, which tell you where they came from.

Jasper in Banded Iron Formations

Jasper is a key part of special rocks called banded iron formations, or BIFs. These rocks have distinct layers of different colors. The red bands in BIFs are actually a type of red jasper. These formations tell us about Earth's ancient past. They show that there was some oxygen in the oceans when these rocks formed, like during the Great Oxygenation Event millions of years ago.

Picture Jaspers: Nature's Art

Earrings made from polished "leopard-spot jasper." This type of rock often has patterns that look like animal spots.

Picture jaspers are amazing! They have patterns that look like tiny landscapes or scenes when you look at a cut piece. These patterns can be stripes from how the rock flowed or settled. They can also be tree-like shapes or different color swirls. Sometimes, colors spread out from a center point, making a round, "orbicular" pattern. This is seen in "leopard skin jasper."

You can find these "picture jaspers" all over the world. But certain colors or patterns are special to specific places. For example, Indonesia is a source, especially in the Purbalingga district. In the United States, Oregon's Biggs jasper and Idaho's Bruneau jasper are famous for their beautiful patterns. You can also find examples in Wales and a blue-green jasper in Russia.

Basanite: The Ancient Touchstone

Basanite is a special black rock that looks like jasper. It was known as the "Lydian stone" or "touchstone" in ancient times. People used it to test if precious metals like gold were pure. They would rub the metal on the dark stone. The color of the streak left behind would tell them how pure the metal was. This method was described by ancient writers like Theophrastus over 2,000 years ago.

Gallery

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  Red jasper rough, Cave Creek, Arizona

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  Dull red jasper veined with white quartz, rough, provenance: uncertain – possibly Crimea or Kyrgyzstan

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  Brecciated red jasper tumbled smooth, 1 in (2.5 cm)

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  Red-green-and-yellow jasper cabochon, Cherry Creek, China

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  Brecciated yellow-and-green jasper, cut and polished, Kara Dag, Crimea

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  Brecciated yellow jasper, cut and oiled

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  Green-yellow-and-orange polished jasper boulder, Tropical Parc, musée des mineraux, Saint-Jacut-les-Pins, Brittany

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  Green-and-red jasper pebble with areas of grey, translucent chalcedony, Aomori Prefecture, Shichiri Nagahama, Japan

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  Cabochon of Tabu Tabu jasper (brecciated, with angular clasts cemented by grey chalcedony) South Africa

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  Jasper variety bloodstone, provenance doubtful, possibly Deccan Traps India

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  Multi-coloured, banded jasper rough, Montjuïc, Barcelona

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  Kaleidoscope jasper rough, Oregon

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  Poppy jasper (an orbicular jasper from Morgan Hill, California), rough

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  Poppy jasper: small, polished slabs, Morgan Hill, California

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  Orbicular "ocean jasper" (not, strictly, a jasper, but a highly silicified rhyolite or tuff) Analalava District Madagascar, polished slab

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  Orbicular "ocean jasper", 5 cm (2.0 in), Analalava District, Madagascar

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  Bruneau jasper, Idaho (this jasper occurs within thundereggs), A. E. Seaman Mineral Museum

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  "Mookaite" (a radiolarian chert from the Windalia Radiolarite Formation, Western Australia), rough

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  Biggs jasper, Oregon

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  "Dalmatian jasper" – not a jasper at all but a form of the igneous rock perthite. The black spots are composed of the rare amphibole arfvedsonite (and not, as often claimed, of tourmaline). Polished pebble.