Jasper

Last updated

Jasper
Jasper outcrop in the Bucegi Mountains.jpg
Jasper outcrop, Bucegi Mountains, Romania
General
Category Mineral
Formula
(repeating unit)
SiO2 (with varying impurities)
Crystal system Hexagonal
Crystal class Quartz (Chalcedony)
Identification
ColourMost commonly red, but may be yellow, brown, green or (rarely) blue
Cleavage Indiscernible
Mohs scale hardness6.5–7
Luster Vitreous
Diaphaneity Opaque
Specific gravity 2.5–2.9
Refractive index 1.54–2.65
Birefringence 0.009

Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, [1] [2] is an opaque, [3] impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The specific gravity of jasper is typically 2.5 to 2.9 g/cm³. [4] Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.

Contents

Etymology and history

Movable Egyptian ring in green jasper and gold, from 664 to 322 BC or later (Late Period), the Walters Art Museum Egyptian - Finger Ring with a Representation of Ptah - Walters 42387 - Side A.jpg
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, provenance unknown, Royal Pump Room, Harrogate Red jasper amulet HARGM7392.JPG
Amulet of scarlet jasper, provenance unknown, Royal Pump Room, Harrogate
Low-relief sphinx pendant, red jasper, pearl and enamel, French, circa 1870 Necklace And Pendant (possibly France), ca. 1870 (CH 18423329).jpg
Low-relief sphinx pendant, red jasper, pearl and enamel, French, circa 1870

The name means "spotted or speckled stone," and is derived via Old French jaspre (variant of Anglo-Norman jaspe) and Latin iaspidem (nom. iaspis) from Greek ἴασπιςiaspis (feminine noun), [6] from an Afroasiatic language (cf. Hebrew ישפהyashpeh, Akkadian yashupu). [7] This Semitic etymology is believed to be unrelated to that of the English given name Jasper, which is of Persian origin, [8] [lower-alpha 1] though the Persian word for the mineral jasper is also yashp (یَشم).

Green jasper was used to make bow drills in Mehrgarh between 4th and 5th millennium BC. [9] Jasper is known to have been a favorite gem in the ancient world; its name can be traced back in Arabic, Persian, Hebrew, Assyrian, Greek and Latin. [10] On Minoan Crete, jasper was carved to produce seals circa 1800 BC, as evidenced by archaeological recoveries at the palace of Knossos. [11]

Although the term jasper is now restricted to opaque quartz, the ancient iaspis was a stone of considerable translucency including nephrite. [2] The jasper of antiquity was in many cases distinctly green, for it is often compared to emerald and other green objects. Jasper is referred to in the Nibelungenlied as being clear and green. The jasper of the ancients probably included stones which would now be classed as chalcedony, and the emerald-like jasper may have been akin to the modern chrysoprase. The Hebrew word may have designated a green jasper. [12] Flinders Petrie suggested that the odem – the first stone on the High Priest's breastplate – was a red jasper, whilst tarshish, the tenth stone, may have been a yellow jasper. [13]

Male torso carved from red jasper, Bronze Age, Harappa, Indus Valley civilisation, Pakistan Harappa red jasper male torso.jpg
Male torso carved from red jasper, Bronze Age, Harappa, Indus Valley civilisation, Pakistan

Types

Jewel-set vase carved from red-and-yellow jasper. Probable provenance: German, early 17th century, Waddesdon Bequest, British Museum Jasper vase WB.71.jpg
Jewel-set vase carved from red-and-yellow jasper. Probable provenance: German, early 17th century, Waddesdon Bequest, British Museum
Goat-headed basket carved from red jasper. Russian, late 19th century, Kremlin Armoury Jasper goat basket (Russia, 19 c.).jpg
Goat-headed basket carved from red jasper. Russian, late 19th century, Kremlin Armoury

Jasper is an opaque rock of virtually any colour stemming from the mineral content of the original sediments or ash. Patterns arise during the consolidation process forming flow and depositional patterns in the original silica-rich sediment or volcanic ash. Hydrothermal circulation is generally thought to be required in the formation of jasper. [14]

Jasper can be modified by the diffusion of minerals along discontinuities providing the appearance of vegetative growth, i.e., dendritic. The original materials are often fractured and/or distorted, after deposition, into diverse patterns, which are later filled in with other colorful minerals. Weathering, with time, will create intensely colored superficial rinds.

The classification and naming of jasper varieties presents a challenge. [15] Terms attributed to various well-defined materials includes the geographic locality where it is found, sometimes quite restricted such as "Bruneau" (a canyon) and "Lahontan" (a lake), rivers and even individual mountains; many are fanciful, such as "forest fire" or "rainbow", while others are descriptive, such as "autumn" or "porcelain". A few are designated by the place of origin such as a brown Egyptian or red African.

Banded iron formations

Jasper is the main component in the silica-rich parts of banded iron formations (BIFs) which indicate low, but present, amounts of dissolved oxygen in the water such as during the Great Oxidation Event or snowball earths. [16] The red bands are microcrystalline red chert, also called jasper.

Picture jaspers

Earrings of polished "leopard-spot jasper" (actually a type of spherulitic rhyolite) Jasper earrings.jpg
Earrings of polished "leopard-spot jasper" (actually a type of spherulitic rhyolite)

Picture jaspers exhibit combinations of patterns resulting in what appear to be scenes or images, when seen on a cut section. Such patterns include banding from flow or depositional patterns (from water or wind), as well as dendritic or color variations. Diffusion from a center produces a distinctive orbicular appearance, i.e., leopard skin jasper or linear banding from a fracture as seen in liesegang jasper. Healed, fragmented rock produces brecciated (broken) jasper.

While these "picture jaspers" can be found all over the world, specific colors or patterns are unique to the geographic region from which they originate. One source of the stone is Indonesia, especially in Purbalingga district. From the US, Oregon's Biggs jasper and Idaho's Bruneau jasper from the Bruneau River canyon are particularly fine examples. Other examples can be seen at Ynys Llanddwyn in Wales. [17] A blue-green jasper occurs in a deposit at Ettutkan Mountain, Staryi Sibay, Bashkortostan, Russia. (The town of Sibay, in the far south of the Ural Mountains, near the border with Kazakhstan, is noted for its colossal, open-cast copper mine.) [18]

Basanite and other types of touchstone

Basanite is a deep velvety-black variety of amorphous quartz, of a slightly tougher and finer grain than jasper, and less splintery than hornstone. It was the Lydian stone or touchstone of the ancients. It is mentioned and its use described in the writings of Bacchylides about 450 BC, and was also described by Theophrastus in his book On Stones (Ancient Greek title: Περὶ λίθων: Peri Lithon), a century later. It is evident that the touchstone that Pliny had in mind when he wrote about it was merely a dense variety of basalt. [19]

Basanite (not to be confused with bassanite), Lydian stone, and radiolarite (a.k.a. lydite or flinty slate) are terms used to refer to several types of black, jasper-like rock (also including tuffs, cherts and siltstones) [20] which are dense, fine-grained and flinty / cherty in texture and found in a number of localities. The "Lydian Stone" known to the Ancient Greeks is named for the ancient kingdom of Lydia in what is now western Turkey. A similar rock type occurs in New England. Such rock types have long been used for the making of touchstones to test the purity of precious metal alloys, because they are hard enough to scratch such metals, which, if drawn (scraped) across them, show to advantage their metallic streaks of various (diagnostic) colours, against the dark background. There are, confusingly, not one but two rocks called basanite, one being a black form of jasper and the other a black volcanic rock closely akin to basalt. Add to this the fact that many different rock types – having in common the colour black and a fine texture – have, over the ages, been pressed into service as touchstones and it will be seen that there is ample scope for confusion in this petrology- and mineralogy-related field of study. [21]

Footnotes

  1. "Jasper: The usual English form of the name assigned in Christian folklore to one of the three magi or 'wise men', who brought gifts to the infant Christ at his birth (Matthew 2:1). The name [Jasper] does not appear in the Bible, and is first found in medieval tradition. It seems to be ultimately of Persian origin, from a word meaning 'treasurer'. There is probably no connection with the English vocabulary word jasper denoting a gemstone, which is of Semitic origin." — Hanks, Hardcastle, & Hodges (2006) [8]

Related Research Articles

<span class="mw-page-title-main">Agate</span> Rock consisting of cryptocrystalline silica alternating with microgranular quartz

Agate is the banded variety of chalcedony, which comes in a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate was common in Ancient Greece, in assorted jewelry and in the seal stones of Greek warriors, while bead necklaces with pierced and polished agate date back to the 3rd millennium BCE in the Indus Valley civilisation.

<span class="mw-page-title-main">Gemstone</span> Piece of mineral crystal used to make jewelry

A gemstone is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments. However, certain rocks and occasionally organic materials that are not minerals are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity and notoriety are other characteristics that lend value to gemstones.

<span class="mw-page-title-main">Topaz</span> Silicate mineral

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can make it pale blue or golden brown to yellow orange. Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple.

<span class="mw-page-title-main">Chalcedony</span> Microcrystalline varieties of silica

Chalcedony ( kal-SED-ə-nee, or KAL-sə-doh-nee) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide).

<span class="mw-page-title-main">Chrysoberyl</span> Mineral or gemstone of beryllium aluminate

The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula BeAl2O4. The name chrysoberyl is derived from the Greek words χρυσός chrysos and βήρυλλος beryllos, meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and beryl are two completely different gemstones, although they both contain beryllium. Chrysoberyl is the third-hardest frequently encountered natural gemstone and lies at 8.5 on the Mohs scale of mineral hardness, between corundum (9) and topaz (8).

Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin lux, meaning "light", and generally implies radiance, gloss, or brilliance.

<span class="mw-page-title-main">Chert</span> Hard, fine-grained sedimentary rock composed of cryptocrystalline silica

Chert is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.

<span class="mw-page-title-main">Tiger's eye</span> Chatoyant gemstone from the quartz family

Tiger's eye is a chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown colour and a silky lustre. As members of the quartz group, tiger's eye and the related blue-coloured mineral hawk's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered amphibole fibres that have mostly turned into limonite.

<span class="mw-page-title-main">Onyx</span> Banded variety

Onyx is the parallel-banded variety of chalcedony, an oxide mineral. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands; agate has curved bands while onyx has parallel bands. The colors of its bands range from black to almost every color. Specimens of onyx commonly contain bands of black and/or white. Onyx, as a descriptive term, has also been applied to parallel-banded varieties of alabaster, marble, calcite, obsidian, and opal, and misleadingly to materials with contorted banding, such as "cave onyx" and "Mexican onyx".

<span class="mw-page-title-main">Conchoidal fracture</span> Brittle fracture surface that does not follow any natural planes of separation

A conchoidal fracture is a break or fracture of a brittle material that does not follow any natural planes of separation. Mindat.org defines conchoidal fracture as follows: "a fracture with smooth, curved surfaces, typically slightly concave, showing concentric undulations resembling the lines of growth of a shell". Materials that break in this way include quartz, chert, flint, quartzite, jasper, and other fine-grained or amorphous materials with a composition of pure silica, such as obsidian and window glass, as well as a few metals, such as solid gallium.

<span class="mw-page-title-main">Jadeite</span> Pyroxene mineral

Jadeite is a pyroxene mineral with composition NaAlSi2O6. It is hard (Mohs hardness of about 6.5 to 7.0), very tough, and dense, with a specific gravity of about 3.4. It is found in a wide range of colors, but is most often found in shades of green or white. Jadeite is formed only in the subduction zones of continental margins, where rock undergoes metamorphism at high pressure but relatively low temperature.

<span class="mw-page-title-main">Priestly breastplate</span> Jewish ritual object worn by the High Priest

The priestly breastplate or breastpiece of judgment was a sacred breastplate worn by the High Priest of the Israelites, according to the Book of Exodus. In the biblical account, the breastplate is termed the breastplate of judgment, because the Urim and Thummim were placed upon it. These elements of the breastplate are said in the Exodus verse to carry the judgement of God concerning the Israelites at all times.

<span class="mw-page-title-main">Grossular</span> Garnet, nesosilicate mineral

Grossular is a calcium-aluminium species of the garnet group of minerals. It has the chemical formula of Ca3Al2(SiO4)3 but the calcium may, in part, be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from the botanical name for the gooseberry, grossularia, in reference to the green garnet of this composition that is found in Siberia. Other shades include cinnamon brown (cinnamon stone variety), red, and yellow. Grossular is a gemstone.

<span class="mw-page-title-main">Prasiolite</span> Mineral, quartz variety

Prasiolite is a green variety of quartz.

<span class="mw-page-title-main">Lake Superior agate</span>

The Lake Superior agate is a type of agate stained by iron and found on the shores of Lake Superior. Its wide distribution and iron-rich bands of color reflect the gemstone's geologic history in Minnesota, Wisconsin, Nebraska, Iowa, Kansas and Michigan. In 1969 the Lake Superior agate was designated by the Minnesota Legislature as the official state gemstone.

<span class="mw-page-title-main">Pietersite</span> Commercial term for a variety of chalcedony

Pietersite is a commercial term for a variety of the mineral chalcedony. Originating from Namibia and China, where it is mined for use as a decorative stone due to its chaotic chatoyancy and brecciated structure.

<span class="mw-page-title-main">Bruneau jasper</span> Variety of the mineral jasper

Bruneau jasper is a variety of the mineral jasper. It is a "picture jasper" – a jasper that exhibits particular patterns and colors – and is used as an opaque gemstone.

A range of gemstones are mentioned in the Bible, particularly in the Old Testament and the Book of Revelation. Much has been written about the precise identification of these stones, although largely speculative.

<span class="mw-page-title-main">Fairburn Agate</span> Gemstone with concentric layers of cryptocrystalline chalcedony

The Fairburn Agate is a type of gemstone found in the agate beds of Southwestern South Dakota and Northwestern Nebraska. It is also the state gemstone of South Dakota. Fairburns are characterized from other types of agate by their colors and the shape of the bands.

References

  1. "Chalcedony". Gemstones. USGS.gov. Commodity minerals. U.S. Geological Survey.
  2. 1 2 Kostov, R.I. (2010). Review on the mineralogical systematics of jasper and related rocks (PDF). Archaeometry Workshop. Vol. 7. pp. 209–213.
  3. "Jasper". Mindat.org.
  4. Dietrich, R.V. (23 May 2005). "Jasper". cst.cmich.edu. GemRocks. Central Michigan University. Archived from the original on 9 March 2012. Retrieved 16 October 2006.
  5. "Finger ring with a representation of Ptah". The Walters Art Museum.
  6. "iaspis". Lexicon. Blue Letter Bible. Strong's G2393. Archived from the original on 22 May 2016.
  7. "Jasper". etymonline.com.
  8. 1 2 Hanks, Patrick; Hardcastle, Kate; Hodges, Flavia (2006). A Dictionary of First Names (2 ed.). Oxford University Press. p. 138. ISBN   978-0198610601.
  9. Kulke, Hermann; Rothermund, Dietmar (2004). A History of India. Routledge. p. 22. ISBN   0-415-32920-5.
  10. "Jasper". Gem by Gem. International Colored Gemstone Association.
  11. Hogan, C. Michael (14 April 2008). "Knossos fieldnotes". The Modern Antiquarian.
  12. 1 2 Wikisource-logo.svg One or more of the preceding sentences incorporates text from a publication now in the public domain : Rudler, Frederick William (1911). "Jasper". In Chisholm, Hugh (ed.). Encyclopædia Britannica (11th ed.). Cambridge University Press.
  13. Hastings's Dict. Bible. 1902, cited in Encyclopedia Britannica (1911). [12] .
  14. "Jasper". Prehistoric Online. Retrieved 10 June 2022.
  15. Gamma, Hans (ed.). "World of Jaspers". worldofjaspers.com (main).
  16. Broecker, W.S. (1985). How to Build a Habitable Planet.
  17. "Jasper gemological information". gemsociety.org. International Gem Society (IGS). Retrieved 16 January 2015.
  18. "[green] Jasper from Ettutkanskoe jasper deposit, Ettutkan Mt, Staryi Sibay, Bashkortostan, Russia". Mindat.org. Retrieved 21 April 2020.
  19. Dake, H.C.; Fleener, Frank L.; Wilson, Ben Hur (1938). Quartz Family Minerals: A handbook for the mineral collector. Whittlesey House (McGraw Hill).
  20. Moore, D.T.; Oddy, W.A. (1 January 1985). "Touchstones: Some aspects of their nomenclature, petrography and provenance". Journal of Archaeological Science. 12 (1): 59–80. Bibcode:1985JArSc..12...59M. doi:10.1016/0305-4403(85)90015-9.
  21. "Basanite". Mindat.org. 15 October 2012. Retrieved 24 March 2013.