Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K 3AlSi 3O102. Hausmann in 1847 in honor of the French physicist Jean-Baptiste Biot, magnesium, silicon and hydrogen form sheets that are weakly bound together by potassium ions. It is sometimes called iron mica because it is more iron-rich than phlogopite and it is sometimes called black mica as opposed to white mica – both form in some rocks, and in some instances side-by-side. Like other mica minerals, biotite has a perfect basal cleavage, and consists of flexible sheets, or lamellae. It has a crystal system, with tabular to prismatic crystals with an obvious pinacoid termination. It has four faces and two pinacoid faces to form a pseudohexagonal crystal. Although not easily seen because of the cleavage and sheets, fracture is uneven and it appears greenish to brown or black, and even yellow when weathered. It can be transparent to opaque, has a vitreous to pearly luster, when biotite is found in large chunks, they are called “books” because it resembles a book with pages of many sheets.
The color of biotite is usually black and the mineral has a hardness of 2. 5-3 on the Mohs scale of mineral hardness, biotite dissolves in both acid and alkaline aqueous solutions, with the highest dissolution rates at low pH. However, biotite dissolution is highly anisotropic with crystal edge surfaces reacting 45 to 132 times faster than basal surfaces, under cross-polarized light biotite can generally be identified by the gnarled birds eye extinction. Biotite is found in a variety of igneous and metamorphic rocks. For instance, biotite occurs in the lava of Mount Vesuvius, biotite in granite tends to be poorer in magnesium than the biotite found in its volcanic equivalent, rhyolite. Biotite is an essential phenocryst in some varieties of lamprophyre, biotite is occasionally found in large cleavable crystals, especially in pegmatite veins, as in New England and North Carolina. Other notable occurrences include Bancroft and Sudbury, Ontario and it is an essential constituent of many metamorphic schists, and it forms in suitable compositions over a wide range of pressure and temperature.
It has been estimated that biotite comprises up to 7% of the continental crust. The largest documented single crystals of biotite were approximately 7 m2 sheets found in Iveland, biotite is used extensively to constrain ages of rocks, by either potassium-argon dating or argon-argon dating. Because argon escapes readily from the crystal structure at high temperatures. Biotite is useful in assessing temperature histories of metamorphic rocks, because the partitioning of iron and magnesium between biotite and garnet is sensitive to temperature
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava, the magma can be derived from partial melts of existing rocks in either a planets mantle or crust. Typically, the melting is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks and metamorphic rocks make up 90–95% of the top 16 km of the Earths crust by volume. Igneous rocks form about 15% of the Earths current land surface, most of the Earths oceanic crust is made of igneous rock. In terms of modes of occurrence, igneous rocks can be either intrusive or extrusive, the mineral grains in such rocks can generally be identified with the naked eye.
Intrusive rocks can be classified according to the shape and size of the intrusive body, typical intrusive formations are batholiths, laccoliths and dikes. When the magma solidifies within the earths crust, it cools slowly forming coarse textured rocks, such as granite, the central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores may occupy huge areas of the Earths surface, intrusive igneous rocks that form at depth within the crust are termed plutonic rocks and are usually coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks, hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, laccoliths, lopoliths, or phacoliths. Extrusive igneous rocks, known as rocks, are formed at the crusts surface as a result of the partial melting of rocks within the mantle. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks and they are formed by the cooling of molten magma on the earths surface.
The magma, which is brought to the surface through fissures or volcanic eruptions, hence such rocks are smooth and fine-grained. Basalt is an extrusive igneous rock and forms lava flows, lava sheets. Some kinds of basalt solidify to form long polygonal columns, the Giants Causeway in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma and it rises because it is less dense than the rock from which it was created. When magma reaches the surface from beneath water or air, it is called lava, eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ocean are termed submarine. Black smokers and mid-ocean ridge basalt are examples of volcanic activity
The Koster Islands situated 10 km west of Strömstad, comprises an archipelago surrounding the two largest islands, South Koster and North Koster. South Koster has an area of 8 km² and North Koster an area of 4 km², the landscape, dominated by smooth bedrock, bears witness to volcanic activity and subsequent wear due to the Ice Age. The rocky coastline is broken by many sandy beaches the largest being Kilesand on South Kosters east side overlooking the 200 meter deep Koster Fjord and North Koster are communities with a permanent population of around 340. There is a school, sports hall, church, both farming and fishing are important, and already during the 1600s Koster exported lobster to Holland. There are several small harbors, popular with sailors from both near and far, rooms can be rented from the Ekenäs Hotel or from private homes or cabins. There is a campsite on North Koster, an electrically driven ferry operates constantly between the two islands, a distance of 58 meters. As one moves inland, farmland and rich vegetation becomes apparent, South Koster has a network of roads and paths, which can be explored by bicycle or in small golf-buggies, both of which can be rented.
On North Koster it is possible to rent small boats. Restrictions regarding the right of access, Allemansrätten, forbid open fires, the Koster Islands have a marine west coast climate that has a narrower range of temperatures than inland and areas on the east coast on similar parallels. Still yet, sleet was recorded on Nordkoster as late as June 12,1981, Koster is a well-established and popular tourist destination, attracting as many as 90000 tourists each year, renowned for being one of Swedens sunniest places offering bathing opportunities. During the summer there are a variety of events and activities, such as a festival, mackerel race. Several pubs and restaurants offer a menu, often based on seafood from local fisherman, such as shrimp, crayfish, crab. Connections to the mainland are good with 16 ferry departures daily from Strömstad, private cars can be parked at the car park just outside the center of Strömstad from where buses run free of charge to the square where the harbor lies. Kosterbladet 2010 Koster, Islands in the Skagerrak Map of Koster Islands
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the four elements in the silicate lattice, Mg, Fe, Ni. Clinochlore, O108 Chamosite, O108 Nimite, O108 Pennantite, 64O108 In addition, lithium, the great range in composition results in considerable variation in physical, and X-ray properties. Similarly, the range of chemical composition allows chlorite group minerals to exist over a range of temperature and pressure conditions. For this reason chlorite minerals are ubiquitous minerals within low and medium temperature metamorphic rocks, some rocks, hydrothermal rocks. The name chlorite is from the Greek chloros, meaning green, the typical general formula is, 34O102·36. This formula emphasizes the structure of the group, chlorites have a 2,1 sandwich structure, this is often referred to as a talc layer. Unlike other 2,1 clay minerals, a chlorites interlayer space is composed of 6 and this 6 unit is more commonly referred to as the brucite-like layer, due to its closer resemblance to the mineral brucite.
Therefore, chlorites structure appears as follows, -t-o-t-brucite-t-o-t-brucite, thats why they are called 2,1,1 minerals. An older classification divided the chlorites into two subgroups, the orthochlorites and leptochlorites, the terms are seldom used and the ortho prefix is somewhat misleading as the chlorite crystal system is monoclinic and not orthorhombic. Chlorite is commonly found in rocks as an alteration product of mafic minerals such as pyroxene, amphibole. Chlorite is a common mineral associated with ore deposits and commonly occurs with epidote, adularia. Chlorite is a metamorphic mineral, usually indicative of low-grade metamorphism. It is the species of the zeolite facies and of lower greenschist facies. It occurs in the quartz, sericite, within ultramafic rocks, metamorphism can produce predominantly clinochlore chlorite in association with talc. Chlorite occurs naturally in a variety of locations and forms, for example, chlorite is found naturally in certain parts of Wales in mineral schists.
Chlorite is found in large boulders scattered on the surface on Ring Mountain in Marin County. Clinoclore and chamosite are the most common varieties, several other sub-varieties have been described
Migmatite is a rock that is a mixture of metamorphic rock and igneous rock. They can be known as diatexite, Migmatites form under extreme temperature conditions during prograde metamorphism, where partial melting occurs in pre-existing rocks. Migmatites are not crystallized from a molten material, and are not generally the result of solid-state reactions. Commonly, migmatites occur within extremely deformed rocks that represent the base of eroded mountain chains, if present, the mesosome, intermediate in color between a leucosome and melanosome, is mostly a more or less unmodified remnant of the original parent rock. The light-colored material has the appearance of having been mobilized or molten, a leucosome is the lightest-colored part of migmatite. The melanosome is the part, and occurs between two leucosomes or, if remnants of the more or less unmodified parent rock are still present. When present, the mesosome is intermediate in color between leucosome and melanosome, migmatite textures are the product of thermal softening of the metamorphic rocks.
Schlieren textures are a common example of granite formation in migmatites. Ptygmatic folds are formed by highly plastic ductile deformation of the gneissic banding, ptygmatic folds can occur restricted to compositional zones of the migmatite, for instance in fine-grained shale protoliths versus in coarse granoblastic sandy protolith. When a rock undergoes partial melting some minerals will melt, while others remain solid, the neosome is composed of lightly-colored areas and dark areas. The leucosome lies in the center of the layers and is composed of quartz. The melanosome is composed of cordierite and biotite and forms the wall zones of the neosome, for migmatised argillaceous rocks, the partial or fractional melting would first produce a volatile and incompatible-element enriched rich partial melt of granitic composition. Such granites derived from sedimentary rock protoliths would be termed S-type granite, are typically potassic, sometimes containing leucite, volcanic equivalents would be rhyolite and rhyodacite.
Volcanic equivalents would be dacite and trachydacite and it is difficult to melt mafic metamorphic rocks except in the lower mantle, so it is rare to see migmatitic textures in such rocks. However and granulite are roughly equivalent mafic rocks, the Finnish petrologist Jakob Sederholm first used the term in 1907 for rocks within the Scandinavian craton in southern Finland. The term was derived from the Greek word μιγμα, migma meaning a mixture, the Canadian Mineralogist Special Publication 9. Mineralogical Association of Canada, Quebec, NRC Research Press, Ottawa, ISBN 978-0-660-19787-6 Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks,6. Migmatites and related rocks R. V. Dietrich - Migmatites North Cascades National Park and Migmatites Cooma Complex, SE Australia
Kyanite is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than four kilobars, kyanite is known as disthene and cyanite. Kyanite is a member of the series, which includes the polymorph andalusite. Kyanite is strongly anisotropic, in that its hardness varies depending on its crystallographic direction, in kyanite, this anisotropism can be considered an identifying characteristic. At temperatures above 1100 °C kyanite decomposes into mullite and vitreous silica via the reaction,3 → 3Al2O3·2SiO2 + SiO2. This transformation results in an expansion and its name comes from the same origin as that of the color cyan, being derived from the Ancient Greek word κύανος. This is generally rendered into English as kyanos or kuanos and means dark blue, kyanite is used primarily in refractory and ceramic products, including porcelain plumbing fixtures and dishware. It is used in electronics, electrical insulators and abrasives, kyanite has been used as a semiprecious gemstone, which may display cats eye chatoyancy, though this use is limited by its anisotropism and perfect cleavage.
Color varieties include recently discovered orange kyanite from Tanzania, the orange color is due to inclusion of small amounts of manganese in the structure. Kyanite is one of the minerals that are used to estimate the temperature, depth. Kyanites elongated, columnar crystals are usually a good first indication of the mineral, associated minerals are useful as well, especially the presence of the polymorphs of staurolite, which occur frequently with kyanite. However, the most useful characteristic in identifying kyanite is its anisotropism, kyanite occurs in gneiss, schist and quartz veins resulting from high pressure regional metamorphism of principally pelitic rocks. It occurs as detrital grains in sedimentary rocks and it occurs associated with staurolite, sillimanite, hornblende, gedrite and corundum. Kyanite occurs in Manhattan schist, formed under extreme pressure as a result of the two landmasses that formed supercontinent Pangaea
South Carolina /ˌsaʊθ kærəˈlaɪnə/ is a state in the southeastern region of the United States. The state is bordered to the north by North Carolina, to the south and west by Georgia across the Savannah River, South Carolina became the eighth state to ratify the U. S. Constitution, doing so on May 23,1788. South Carolina became the first state to vote to secede from the Union on December 20,1860, after the American Civil War, it was readmitted into the United States on June 25,1868. South Carolina is the 40th most extensive and the 23rd most populous U. S. state and its GDP as of 2013 was $183.6 billion, with an annual growth rate of 3. 13%. The capital and largest city is Columbia with a 2013 population of 133,358, South Carolina is named in honor of King Charles I of England, under whose reign the English colony was first formed, with Carolus being Latin for Charles. There is evidence of activity in the area about 12000 years ago. Along the Savannah River were the Apalachee and the Yamasee, further west were the Cherokee, and along the Catawba River, the Catawba.
These tribes were village-dwellers, relying on agriculture as their food source. The Cherokee lived in wattle and daub houses made with wood and clay, about a dozen separate small tribes summered on the coast harvesting oysters and fish, and cultivating corn and beans. Travelling inland as much as 50 miles mostly by canoe, they wintered on the plain, hunting deer and gathering nuts. The names of these survive in place names like Edisto Island, Kiawah Island. The Spanish were the first Europeans in the area, in 1521, founding San Miguel de Gualdape, established with 500 settlers, it was abandoned within a year by 150 survivors. In 1562 French settlers established a settlement at what is now the Charlesfort-Santa Elena archaeological site on Parris Island, three years the Spanish built a fort on the same site, but withdrew following hostilities with the English navy. In 1629, King Charles I of England established the Province of Carolina an area covering what is now South and North Carolina, Georgia, in the 1670s, English planters from the Barbados established themselves near what is now Charleston.
Settlers built rice plantations in the South Carolina Lowcountry, east of the Atlantic Seaboard fall line, settlers came from all over Europe. Plantation labor was done by African slaves who formed the majority of the population by 1720, another cash crop was the Indigo plant, a plant source of blue dye, developed by Eliza Lucas. Meanwhile, in Upstate South Carolina, west of the Fall Line, was settled by farmers and traders. Colonists overthrew the rule, seeing more direct representation
Sandstone is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains. Most sandstone is composed of quartz or feldspar because these are the most common minerals in the Earths crust, like sand, sandstone may be any color, but the most common colors are tan, yellow, grey, pink and black. Since sandstone beds often form highly visible cliffs and other topographic features, quartz-bearing sandstone is converted into quartzite through heating and pressure, usually related to tectonic compression within orogenic belts. They are formed from cemented grains that may either be fragments of a rock or be mono-minerallic crystals. The cements binding these grains together are typically calcite, grain sizes in sands are defined within the range of 0.0625 mm to 2 mm. The formation of sandstone involves two principal stages, first, a layer or layers of sand accumulates as the result of sedimentation, either from water or from air. Typically, sedimentation occurs by the settling out from suspension.
The most common cementing materials are silica and calcium carbonate, which are derived either from dissolution or from alteration of the sand after it was buried. Colours will usually be tan or yellow, a predominant additional colourant in the southwestern United States is iron oxide, which imparts reddish tints ranging from pink to dark red, with additional manganese imparting a purplish hue. Red sandstones are seen in the Southwest and West of Britain, as well as central Europe. The regularity of the latter favours use as a source for masonry, either as a building material or as a facing stone. These physical properties allow the grains to survive multiple recycling events. Quartz grains evolve from rock, which are felsic in origin. Feldspathic framework grains are commonly the second most abundant mineral in sandstones, Feldspar can be divided into two smaller subdivisions, alkali feldspars and plagioclase feldspars. The different types of feldspar can be distinguished under a petrographic microscope, below is a description of the different types of feldspar.
Alkali feldspar is a group of minerals in which the composition of the mineral can range from KAlSi3O8 to NaAlSi3O8. Plagioclase feldspar is a group of solid solution minerals that range in composition from NaAlSi3O8 to CaAl2Si2O8. Lithic framework grains are pieces of ancient source rock that have yet to weather away to individual mineral grains, accessory minerals are all other mineral grains in a sandstone, commonly these minerals make up just a small percentage of the grains in a sandstone
The mica group of sheet silicate minerals includes several closely related materials having nearly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition, the nearly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet-like arrangement of its atoms. The word mica is derived from the Latin word mica, meaning a crumb, and probably influenced by micare, to glitter. Chemically, micas can be given the general formula X2Y4–6Z8O204 in which X is K, Na, or Ca or less commonly Ba, Rb, or Cs, Y is Al, Mg, or Fe or less commonly Mn, Cr, Ti, Li, etc. Z is chiefly Si or Al, but may include Fe3+ or Ti, micas can be classed as dioctahedral and trioctahedral. If the X ion is K or Na, the mica is a common mica, whereas if the X ion is Ca, mica is widely distributed and occurs in igneous and sedimentary regimes. Large crystals of mica used for various applications are typically mined from granitic pegmatites, until the 19th century, large crystals of mica were quite rare and expensive as a result of the limited supply in Europe.
However, their price dramatically dropped when large reserves were found and mined in Africa, the largest documented single crystal of mica was found in Lacey Mine, Canada, it measured 10 ×4.3 ×4.3 m and weighed about 330 tonnes. Similar-sized crystals were found in Karelia, Russia. The British Geological Survey reported that as of 2005, Koderma district in Jharkhand state in India had the largest deposits of mica in the world. China was the top producer of mica with almost a third of the share, closely followed by the US, South Korea. Large deposits of mica were mined in New England from the 19th century to the 1970s. Large mines existed in Connecticut, New Hampshire, and Maine and flake mica is produced all over the world. In 2010, the producers were Russia, United States, South Korea, France. The total production was 350,000 t, although no data were available for China. Most sheet mica was produced in India and Russia, flake mica comes from several sources, the metamorphic rock called schist as a byproduct of processing feldspar and kaolin resources, from placer deposits, and from pegmatites.
Sheet mica is considerably less abundant than flake and scrap mica, the most important sources of sheet mica are pegmatite deposits. Sheet mica prices vary with grade and can range from less than $1 per kilogram for low-quality mica to more than $2,000 per kilogram for the highest quality, the mica group represents 37 phyllosilicate minerals that have a layered or platy texture
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of rock-forming minerals and they are classified based on the structure of their silicate groups, which contain different ratios of silicon and oxygen. Nesosilicates, or orthosilicates, have the orthosilicate ion, which constitute isolated 4− tetrahedra that are connected only by interstitial cations and these exist as 3-member 6− and 6-member 12− rings, where T stands for a tetrahedrally coordinated cation. Inosilicates, or chain silicates, have interlocking chains of silicate tetrahedra with either SiO3,1,3 ratio, for single chains or Si4O11,4,11 ratio, for double chains. Nickel–Strunz classification,09. D Pyroxene group Enstatite – orthoferrosilite series Enstatite – MgSiO3 Ferrosilite – FeSiO3 Pigeonite – Ca0.251, all phyllosilicate minerals are hydrated, with either water or hydroxyl groups attached. Serpentine subgroup Antigorite – Mg3Si2O54 Chrysotile – Mg3Si2O54 Lizardite – Mg3Si2O54 Clay minerals group Halloysite – Al2Si2O54 Kaolinite – Al2Si2O54 Illite – 24O10 Montmorillonite –0 and this group comprises nearly 75% of the crust of the Earth.
Tectosilicates, with the exception of the group, are aluminosilicates. Nickel–Strunz classification,09. F and 09. G,04. A, an introduction to the rock-forming minerals. Wise, W. S. Zussman, J. Rock-forming minerals, P.982 pp. Hurlbut, Cornelius S. Danas Manual of Mineralogy. Mindat. org, Dana classification Webmineral, Danas New Silicate Classification Media related to Silicates at Wikimedia Commons
A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin. A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids, the study of minerals is called mineralogy. There are over 5,300 known mineral species, over 5,070 of these have been approved by the International Mineralogical Association, the silicate minerals compose over 90% of the Earths crust. The diversity and abundance of species is controlled by the Earths chemistry. Silicon and oxygen constitute approximately 75% of the Earths crust, which translates directly into the predominance of silicate minerals, minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species, changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals. Minerals can be described by their various properties, which are related to their chemical structure.
Common distinguishing characteristics include crystal structure and habit, lustre, colour, tenacity, fracture, more specific tests for describing minerals include magnetism, taste or smell and reaction to acid. Minerals are classified by key chemical constituents, the two dominant systems are the Dana classification and the Strunz classification, the silicate class of minerals is subdivided into six subclasses by the degree of polymerization in the chemical structure. All silicate minerals have a unit of a 4− silica tetrahedron—that is, a silicon cation coordinated by four oxygen anions. These tetrahedra can be polymerized to give the subclasses, disilicates, inosilicates, other important mineral groups include the native elements, oxides, carbonates and phosphates. The first criterion means that a mineral has to form by a natural process, stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C, modern advances have included extensive study of liquid crystals, which extensively involve mineralogy.
Minerals are chemical compounds, and as such they can be described by fixed or a variable formula, many mineral groups and species are composed of a solid solution, pure substances are not usually found because of contamination or chemical substitution. Finally, the requirement of an ordered atomic arrangement is usually synonymous with crystallinity, crystals are periodic, an ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form and cleavage. There have been recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of an approved by the IMA in 1995, A mineral is an element or chemical compound that is normally crystalline. However, if geological processes were involved in the genesis of the compound, Mineral classification schemes and their definitions are evolving to match recent advances in mineral science
Coll is an island located west of Mull in the Inner Hebrides of Scotland. Coll is known for its beaches, which rise to form large sand dunes, for its corncrakes. It is in the area of Argyll and Bute. Coll is about 13 miles long by 3 miles wide and has a population of around 195, Colls sandy beaches rise to form large sand dunes. Arinagour, is the settlement on the island located at the head of Loch Eatharna. Other inhabited locations include, Acha, a settlement located 5 kilometres south-west of Arinagour. Arileod, located on the west coast,7 kilometres south-west of Arinagour, located 3 kilometres miles north-west of Arinagour. It is the junction for travel between Sorisdale and Arinagour, located on the northern part of Hough Bay,5 kilometres west of Arinagour. Bousd, located 7 kilometres north-east of Arinagour, located on the north-west coast,5 kilometres north-west of Arinagour. Crossapol, located on the south-west coast, located on the west coast 7 kilometres southwest of Arinagour. Uig, located 1 kilometre north-east of the head of Loch Breachacha, Coll is sometimes derived from Gaelic coll, hazel.
However, this does not match the early recorded forms of the name, the name of Coll is given as Colosus in the Life of St Columba by Adamnán, the seventh century abbot of Iona. As /s/ between vowels had been lost in Celtic before Adamnáns time, Watson suggests that Colosus may represent a pre-Celtic name. Richard Coates has proposed that the name may be related to Greek kolossós and may have referred to a standing stone located on the island, like those still seen on North Uist. In Icelandic, the word means a rounded protrusion, such as a rounded mountaintop. Coll was home to a branch of the Clan Maclean for 500 years, in 1583 the Macleans of Duart invaded their cousins on Coll with the intention of taking the island for themselves. The Macleans of Coll retained their fief and Castle of Breacachadh until 1848 when Alexander Maclean of Coll emigrated to Natal. Coll, like other Hebridean islands, has several crannógs located in some of its lochs, one such crannog is Dun Anlaimh, which is thought to date to at least the Middle Ages