Copal

Copal – properties, occurrence, types

Copal is a name given to types of prehistoric conifers or deciduous trees’ resin excavated all over the world. The name derives from a word copali which in Nahuatl language means „incense”. The biggest sources of copals are located in subtropics countries. The biggest advantage of copal is the fact that it is a great material for jewelry and decorative elements production. Copal has been used to produced jewelry by many different cultures all over the world for centuries. Nowadays it is used in professional jewelry making. Sometimes fresh resin collected for medical purposes is also called copal.

Didier Descouens / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)

Properties and occurrence of copal

Copal is characterized by hard mass with the interior that is clear or opaque, while the surface is darker due to air affection. They are well soluble in ethyl alcohol, acetone, ether, and partly in benzene and chloroform. Copals are similar to amber. Just like amber, they may contain organic and nonorganic inclusions. It differs from amber by a lower melting temperature, which leads to different ways of treatment. They are used in the jewelry industry, usually artificially aged to gain yellowish or orangeish color. Sometimes copal is polished to gain additional shine.

Where can copal be found?

Copal, just like amber, can be excavated from the ground, especially its surface layers. Copal is excavated in a form of petite pieces as well as huge chunks. It is a mineral that can be up to a million years old. Some sources claim that copal is 10 000 to 5 million years old. It is worth noting that younger resin is called copra, while the older one is considered as fossil resin. Copal mainly occurs on the Amazon and on the sea coast i.e. America from Mexico to Brazil), in Africa (mainly in its middle belt), in Madagascar, Indonesia, Australia, New Zealand, and New Caledonia.

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Copal types

Copal can be found in many different types, according to the place where they were found.

West African copals

• Sierra Leone – similar to Zanzibar copal in terms of quality and properties, it can be found in spherical chunks. It is characterized by glassy fracture and light colors. It changes its consistency and becomes soft at a temperature of 130-230 degrees. It can be dissolved in amyl alcohol and acetone, and partly in benzene, ethyl, ether, methyl alcohol and carbon tetrachloride.
• Benin – occurs in small, oblong or spherical nuggets that are weathered on the surface and glassy on the edges.
• Accra – occurs in oblong and weathered nuggets on the surface.
• Cameroon – occurs in large lumps that are covered with white dust. It contains clean fractures, and its colors are yellowish or bright red.
• Loango – occurs in irregular lumps with sharp edges with a glassy fracture. It has a weathered surface.
• Gabon – occurs in flat lumps up to 8 cm long. It has a yellowish to blood-red color.
• Angola – occurs in irregular clods with sharp edges. It is characterized by a vast variety of colors such as yellow, red, brown. Some pieces are transparent as well. It softens at 90 degrees and melts at 245 to 305 Celcius degrees.
• Benguela – the last of West African copal occurs in flat or rounded lumps that are slightly wrinkled on the surface.

East African copal

Zanzibar copal is the main type of East African Copal. It is a hard natural resin of the fossil Trachylobium tree. Zanzibar copal occurs in irregular clods that are wrinkled, plate-like, and covered with a brown layer, similar to bark. It occurs at a depth of about a meter below the surface of the ground. The pulp of the described copal is characterized by yellowish or reddish color, as well as its transparency and hardness, which is similar to the hardness of amber. It is worth mention that East African copal softens at 160 degrees and melts at 260 to 300 degrees. It dissolves completely in kajeput oil and partly in ether, benzene, chloroform, toluene, carbon disulfide, as well as rosemary oil and does not dissolve in amyl or methyl alcohol.

South American copal

This type of copal is also called Brazilian copal. It is characterized by a soft structure, the lumps are yellow, greenish or green, covered with a layer similar to the chalk layer. It occurs in Brazil (that is why it is also called Brazilian copal), as well as Venezuela. It is used as an elementary component of some varnishes, medicines, or varnish which is used, for example, in halos.

Kaurian copal

Kurian copal, also known as Kauri copal or New Zeland and New Caledonian copal. It is a hard resin that occurs in brown lumps. Its surface is heavily weathered. It is the most valuable type of copal that occurs in this part of the world. Its characteristic feature is that it dissolved completely in butyl alcohol, as well as in carbon tetrachloride and partly in acetone. It is obtained from New Zeland agate. The New Caledonian copal is a hard resin of the Agathis dammara tree. It occurs in whitish to yellowish colors. Its surface is often covered with a brown coating with a delicate metallic shine. The Philipino copal occurs in heavy lumps that are brown.

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Fossil resin – characteristics

Fossil resin is a product of such processes as oxidation and polymerization of resin acids, which are contained in the juices of conifers pine and cypress trees, Araucarians, and also broadleaf bean species. The polymer content is largely dependent on the environmental conditions in which the resin has become hard. The faster polymerization of acids was undoubtedly influenced by the warm climate. The resin nuggets that were formed under these conditions are clear and brittle. What did marine polymerization look like?

First of all, it was a very long process, which brought many benefits. The resin was harder and has a more stable internal structure. However, due to the relatively high content of microscopic liquid and gas bubbles, it often lost its clarity. What else affected the level of stability of the resin? For example the geological conditions. Fossil resin due to the degree of polymerization can be divided into two groups: amber and copal. How old are they? It is usually impossible to find amber younger than the Miocene amber, which is 7 million years old, and also copal that is older than Pliocene copal which is 5 million years old.

Fossil resin types

There are over 60 types of fossil resin known all over the world. The youngest of them can be found in East America, Africa, Australia, New Zeland, or even Europe. The oldest sources of fossil resin can be found in Canada. It is worth remembering that many types of resin such as Arabic gum, manila copal, mastic, myrrh, sandarach, and dammar resin are artificially produced. Nowadays many chemical, physical genetic, and paleontologic researchers are being widely conducted. Its main idea is to find the mother trees of fossil resin types.

• Ajkait – is a sulfated variety of ruminate containing succinic acid. It occurs in red-brown color and occasionally in light yellow or honey-yellow colors. The color of ajkait is usually opaque, but it sometimes shines yellowish in thin chips.
• Allignit – an amber-like fossil resin that was found in flysch sediments (along the northern border of the Alps in Switzerland and France). It is about 55 million years old.
• Amberite (amborite) – us a type of retinite. It occurs in yellowish, yellow, brown, and dark brown colors. Amberite is transparent and translucent. It has a very delicate and fragile structure. It ignites much simpler than the Kauri copal and burns with a bright, smoky flame. It emits characteristic bituminous smell during this process. It is quite resistant to solvents, it is hard to dissolve. It can be found in lignite deposits that lie between sandstones and Miocene shales in New Zeland. In ancient times, it was obtained in large quantities in mines near Durra, near Auckland on the North Island. It was usually excavated in small crumbs there, sporadically also lumps, even the size of an adult’s head. It could also be found near Auckland in brown coal, which was located on a cliff on the seashore.
• Brumit – is a type of ruminate, which was created about 50 million years ago. It contains up to 2% succinic acid. Brumit can be found in watery-yellow, dark orange, ruby, brown or dark cherry colors. The low amount of succinic acid distinguishes it from other fossil resin types. Its sources are located in the Hukawng Valley, as well as on the Nangotaimaw Hills. It is located in the blue Eocene clays (10-15m deep). It creates irregular, matt lumps. Brumit can be up to 100 million years old, and has special value on the Chinese market! It draws special attention due to the wide range of available colors. It can also be found in Thailand, Malaysia, and Vietnam.
• Bacalit – is a type of fossil resin similar to amber. It occurs in white and yellowish colors. It is insoluble in ether, alcohol, and chloroform. It can be found in the Baja California area of Mexico.
• Baltic amber – is a type of succinite. It is also known as “Baltic gold”. It is usually found in a form of regular nuggets of various sized. The raw material is dug out of the ground and is covered with opaque bark. This type of amber is up to 40 million years old! Baltic amber occurs in various different colors such as light yellow, brown, milky white, blue, greenish, black, and red. It is the most valuable amber type, widely used in the jewelry industry. To exact age of Baltic amber has not been established yet. It is also hard to establish the source tree of resin that created the Baltic amber. Various researches have confirmed up to eleven pine species that were found in amber.
• Austrian amber – it is a type of fossil resin that was found in various regions of Austria. The oldest of them, incorrectly called fossilize, was found in the sediments of the Late Triassic. Varieties such as kaolinite and rosthornite come from Eocene sediments, In the Miocene sediments about 13-14 million years ago, in Goria neat Turnau, as well as the late Miocene about 6-7 million years ago in Zillingdorf, Austria.
• Brazilian amber – it is a type of fossil resin found in Cretaceous deposits in Brazil. Not much is known about this type of amber. It can be found in the Amazon delta.
• Japanese amber – occurs mainly in the northern part of the island of Honshu. In these regions, sources of the raw material are located. It is similar to the Baltic amber but differs from it in the difficulty in processing. Japanese amber is opaque, brown, or dark orange with noticeable little dark spots.
• Dominican amber – is a type of fossil resin that can be found in the Dominican Republic (Haiti Island). It is relatively young, about 16 million years. It is extremely valuable and hard amber. Mostly it is transparent and does not require thermal treatment (up to 90% of the mined raw material). It occurs in intensely orange, honey, or red colors. Dominican amber is a rich source of organic inclusions. Dominican amber is mined in hard-to-reach places, as well as in harsh conditions, only in the dry season. The price of this type of amber is similar to the price of gold.
• Chinese amber – it is a type of fossil resin that occurs in yellow or yellowish-brown color. Its sources are located in Guhengzi Formation (Iprez – around 50 million years), which were mined at the Fushun mine in the Chinese province of Liaoning. Chinese amber is known for a large number of plant inclusions such as seeds, flowers, mushrooms, leaves, pine needles as well as organic animal inclusions such as ants, wasps, bees, ants, crickets, mantis, butterflies, beetles, spiders, centipedes, scorpions or even frogs and lizards.
• Lebanese amber – it is a variety of retinite. It is characterized by light yellow, orange, or dark red color. Sometimes it can be found in cream-white, red, brownish, or black. It occurs both in opaque and transparent forms. It has a delicate, fragile structure, sporadically homogeneous. It is also well known as a rich source of inclusions such as flies, beetles, smaller butterflies, spiders and larvae, pollen, seeds, roots, stems, fungi. It was created from the resin of the Araucarias trees. It can be found in gray sandstone from the early Cretaceous (about 130 million years old) in the regions of Jazzmine, Daher El Baighar, Bireh, and many others.
• North American amber – it is a type of fossil resin found in the rock formations in the United States. The oldest stone of this type comes from the sediments of Chinle Formation in Arizona, as well as New Mexico. It is honey-yellow to black color, mostly transparent. Its mother tree is believed to be the Swamp Cypress. Jelinite, as well as amber found in the coal seams of the Chandler and Prince Creek formation on the rivers Kaolak, Ketik, and Kuk in Alaska, comes from the early Cretaceous. The most popular North American amber includes New Jersey amber that can be found in the Raritan Formation. A little younger type, which is 75 million years old, can be found in the lignite deposits of Fruitland formation in the San Juan Basin in New Mexico. The youngest example of North American amber can be found in the regions of the Hell Creek formation in the region of Glendive in Montana. It occurs in various shades of red. Amber from the state of Maryland is also considered amber of the late Cretaceous.
• Ukrainian amber – it is a variety of succinite, usually occurs in yellow-white, yellow, red, brown-yellow, as well as brown-cherry colors. Most often it is transparent. Sometimes Ukrainian amber is covered with thick, porous, brown bark. As the name implies, Ukrainian amber can be found in Ukraine (up to 50 different places in the western part of this country). It is obtained in huge quantities from the “Pugacz” deposits in Klesow and Vilnius (Near Dobrowik in Volhynia).
• Russian amber – it is a type of fossil resin that occurs in rock formations from various ages in Russia. A variety of popular types comes from the late Cretaceous and occurs on the Taimyr Peninsula in Siberia. It creates small brittle nuggets with a yellow color and transparent structure. Russian amber contains a lot of inclusions. This variety of ruminate can be found in numerous lignite deposits on the island of Sakhalin and on the west coast of the Sea of Okhotsk.
• Tanzanian amber – it is a fossil resin that is older than copal, but younger than Baltic amber.
  Paris Basin amber – it is a fossil resin that occurred in bituminous shale in the early Eocene (about 45 million years ago) in France in the department of Oise. It is characterized by a lack of succinic acid. It usually occurs in yellow and orange. It contains charred pieces of trees of the Aulacoxylon genus.
• Bitterfeld amber – it is a type of succinite that was created in the early Miocene. It is about 22 million years old, among lignite at the “goitsche” opencast mine in the Halle-Leipzig region of Germany. This amber type occurs in brown, black, and yellow. A characteristic feature is numerous organic inclusions such as spiders, beetles, and mites.
• Borne amber – it is another type of fossil resin. It comes from the glessite groups and occurs in lignite deposits from the Middle Miocene (about 15-17 million years ago), which were mined in the state of Sarawak (northern part of the island of Borneo in Malaysia). Borneo amber comes in brown, yellow-brown, red-brown, and in various shades of yellow. There are pieces that include organic inclusions but they are quite rare.
• Chiapas amber (also known as Mexican amber) – it is a type of retinite that was created 25-35 million years ago. It can be found in the sediments from the late Oligocene as well as the early Miocene in the Simojovel area of Chiapas, which is why some call it amber from Chiapas. Its characteristic features are the numerous inclusions contained in it. It resembles Dominican amber in terms of colors and hardness, but sometimes it can be also found in a unique red color, light yellow, light greenish, as well as colorless pieces. The mother tree of Mexican amber was jatoba from the order of Beaners.
• Ghine amber – it is a type of fossil resin (probably an early type of Lebanese amber), which can be found in the sediments of the late Jurassic in Ghine, Lebanon. It is a very rare amber and not much is known about this type.
• New Jersey amber – It is a type of fossil resin that can be found in the glauconite sands of the Raritan Formation (that is 84 million years old), near Sayreville, New Jersey. It is recovered in gravel pits and huge wild clay.
• Tarnobrzeg amber – it is the Polish type of amber from Tarnobrzeg. It is a fossil resin that is largely sulfated (up to 5%). It was found in Sarmatian clays, which were located in the sulfur deposits in Tarnobrzeg.
• Cedarite – it is a type of Canadian amber, which is a variety of retinite. It occurs in brown-honey or yellow-red color and has a fragile and delicate structure. A characteristic feature of this type is the numerous organic inclusions of plants (pollen, seeds, flowers) and animals like insects, mites or spiders. Presumably its mother tree was Araucaria, but this was never confirmed. Cedarite’s sources were primarily located in lignite deposits, then during the Cretaceous period on Lake Grassy in the Albert region, as well as in other places in the province of Saskatchewan in Canada. Cedarite is primarily collected on the beaches (southwest shore of Lake Cedar) in the province of Manitoba in Canada. Cedarite was found in these areas with plant detritus and pieces of lignite. This type of Canadian amber creates numerous round and matted nuggets that reach up to 5 cm in size. It is also found in the Maastricht mountains at Hanson Ranch, near New Castle, Wyoming (United States). .
• Ruminate – as the name implies, it is a type of amber that can be found in Romania. It is a transparent stone that contains numerous cracks. Ruminate usually is red or red-brown. Just like Baltic amber, it is a very valuable stone and widely used in jewelry production, due to its high aesthetic values.
• Symetite – It is a type of amber that occurs in the regions of Sicily. It is about 25 million years old. It is highly valued in jewelry. It occurs in green-yellow or red color with a large number of inclusions. Its natural deposits run out, so often this type of amber is counterfeited.
• Gedanite – it is a type of retninite, which is free of succinic acid. It naturally occurs in slightly yellowish color, sporadically golden-yellow, rarely in darker shades. It can be found in small lumps with a smooth surface. It has a transparent structure, covered with or yellowish-white porous bark. It is delicate and fragile. It is believed that its mother tree was cypress. Gedanite can be found in Baltic amber deposits in the region of Gdansk in Poland.
• Glessyt – it is a variety of retinite, which occurs in reddish-brown or brown color. It has an opaque structure and contains numerous microscopic pores as well as organic inclusions. Glessyt was created from the resin of deciduous trees. It can be found in the old brown coal mines, along with amber goitszite and siegburgite.
• Arabic gum – it is a modern resin, of the Senegalese acacia. It is a mixture of calcium, magnesium, and potassium salts of arabinic acids, tannins, and enzymes. It can be transparent, yellow, or even brown.
• Copal – it is a unique type of resin. Copal is not a type of amber as some might think. It is usually called “fake amber” or “young amber”. However, both stones share some similarities, like tree resin but differ in time of creation. Amber was created about 130 million to 40 million years ago, while copal about 2 million years ago. Unlike amber, copal is soft with a sticky surface and has a characteristic resin aroma. Copal mainly occurs in Africa, Colombia, and the Dominican Republic. It is very valuable due to a large number of inclusions it contains. It is also used to create jewelry but special, advanced treatments are necessary to properly work with that stone. The main types of copals are African copal, Japanese copal, Colombian copal, Kauri copal and Madagascar copal. Copal can also be found in India, Indonesia (Sumatra and Borneo Islands, and Malaysia, and the Philippines.
• African copal – it is fossil resin and a type of copals, which was created in Quaternary deposits about 100,000 years ago. African copal occurs in soil up to a depth of 1m. It can be found in large lumps up to 2 kg. Its mother tree is believed to be a jatoba tree from the legume family. African copal is obtained primarily at the southern tip of Kenya, on the coast of Tanzania, Morocco, Zanzibar, and Israel.
• Japanese copal – it is a type of fossil resin in Pleistocene deposits, about 33 thousand years ago. Japanese has many properties and is believed to be the youngest type of fossil resin. It was discovered during the construction of a highway in the Mizunami area.
• Colombian copal – it is a type of fossil resin from the copal group. It mainly occurs in Quaternary sediments that were formed about 400-600 years ago. Colombian copal usually is yellow, yellow-orange, or transparent. Colombian copal can also be found in northern Mexico, Costa Rica, and southern Brazil. Its largest deposits are located in the Santander province of Colombia.
• Madagascar copal – it is a type of fossil resin that was created in the Quatreranry deposits about 60-50 years ago. It has a light yellow color and contains numerous organic inclusions. It is recovered on the western coasts of Madagascar.
• Kauri copal – it is a fossil resin that occurs in Pleistocene sediments (it is about 10-30 thousand years old). Kauri copal does not contain succinic acid. It is light yellow or transparent. Its structure is fragile and brittle. It is characterized by a large number of insect inclusions. This copal occurs in the north coast of New Zealand.
• Retinite – it is a type of amber, as well as a type of fossil resin. It is characterized by a total lack of succinic acid in its content. There are many subgenres of this stone, which have their own, unique names like, for example, gedanite. It is the second-largest group of amber in the world. How to distinguish retinite from succinite? First of all, by analyzing the infrared spectrum. I both these stones, the curve obtained differs considerably for 8.3 micrometers. According to the latest research, retinite probably completely was formed in terrestrial conditions or in fresh inland waters, which prolonged the polymerization process. Retinite occurs in lignite deposits in Friesdolf, Roisdorf, and many other places in Germany. In Poland, it can be found in Osiek Łużycki, Olszyna near Lubań Slaski, Skorogoszczy near Niemodlin, Radomierzyce near Zgorzekec, as well as near Lwówek Slaski. The retinite group consists of burmit, Lebanese amber, muckit, amber from Tajmyru, Valchovite, Neudorphite, Cedaryt, Gedanite, Gedano-Succinite, Krancite, Dominican Amber, Miocene ambergris, duexite and many others. Japanese amber, koflachite and middletonite are considered retinite as well.
• Copalite – it is a type of fossil resin that was created in the early Cretaceous age. Copalite occurs in sedimentary rock formations (southwestern Europe). The oldest piece was found in small quantities in loam in early Cretaceous on the Isle of Wight. It also occurred in a cliff near Hastings (south-eastern coast of the British Isles). It is mostly brown, available in many different shades, brown-red or red. It is opaque but some pieces might be translucent. It is rich in insect inclusions. The most popular copalite comes from the sediments of the Nograro Formation (Peniacerrade in Cantabria, Alava Spain).
  Krancite – it is a type of retinite that contains 4-6% of sulfur. It occurs in a flexible, soft yellow or white, transparent form. It is covered with yellow bark of varying thickness on the surface. Kraciite is slightly soluble in alcohol (4%) and ether (6%). It is characterized by the content of oval and spherical gas inclusions, and very characteristic smoky flame, emitting an irritating unpleasant and intense smell. It occurs in muddy sands. It can be found in a form of irregular shapes with sharps edges (crumbs reach up to 3 cm).
• Rumenite – it is a type of fossil resin characterized by the low content of succinic acid (about 5%) and quite high sulfur content (above 1%). According to the latest research, rumenites are genetically associated with definite, scraffito, symmetite, and valchovite. Rumenite was created in the early Cretaceous (about 100 million years ago), as well as in the early Oligocene in the southern Carpathian Mountains. It occurs in dark red, brown, brown-red, brown-green, brown-yellow, or rarely in blue color. Sometimes it has pearly opalescence. Rumenite fluoresces in ultraviolet and often contains numerous plant and animal inclusions. The group of rumenite consists of Aikait, Albanian Burmit, amber from the Persian Gulf, amber from Azerbaijan, Paleocene Sakhalin amber as well as muntenite. Rumenite can be found in Cretaceous sediments near Sibiu in the Carpathian Mountains in Romania. They were recovered in large quantities from the Kliwa sandstone in Oligocene underground mines around Colti (northwest of Budapest). Rumenite has occurred there with charred tree fragments. It was also found in Muntei, Dobriż, Oltenia, and other places in Romania. In Poland, however, it was found in flysch sediments (Sanok region).
• Succinite – it is a group of fossil resin that is characterized by the content of succinic acid (3-5%). According to the latest research, it is possible that succinite was created in salty water (as opposed to retimites), which accelerate their polymerization. The succinite group consists of Paleogene Succinite, Chilean Succinite, Amber from Jutralnm Amekite, Baltic Amber, Ukrainian Amber, Miocene amber from Bitterfled and Ambrits of unknown age. Succinite is very strongly polymerized, and easy to process and polish. It forms infiltrative, spherical, droplet, and impregnation forms. It usually occurs in yellow, honey, orange, brown, yellowish-brown, white, sporadically in green, olive green, red, brown-red, blueish, purple, and also black. Succinite can be both transparent and opaque with a waxy, greasy, or glossy finish. It has electrostatic properties and usually contains numerous solid inclusions, i.e. marcasite or other iron compounds, coniferous minerals, soil clods, organic remains of plants and animal, liquid (water), gas (putrefaction gases and air bubbles.

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