21-487: Kollur Mine was a series of gravel - clay pits on the south bank of the Krishna River in the state of Andhra Pradesh , India. It is thought to have produced many large diamonds , known as Golconda diamonds , several of which are or have been a part of crown jewels . The mine was established in the 16th century and operated until the 19th century. Kollur Mine operated between the 16th and mid-19th centuries, and
42-426: A few tens of kilometers of their source outcrops. Gravel is deposited as gravel blankets or bars in stream channels; in alluvial fans ; in near-shore marine settings, where the gravel is supplied by streams or erosion along the coast; and in the deltas of swift-flowing streams. The upper Mississippi embayment contains extensive chert gravels thought to have their origin less than 100 miles (160 km) from
63-644: A high hydraulic conductivity , sometimes reaching above 1 cm/s. Most gravel is derived from disintegration of bedrock as it weathers . Quartz is the most common mineral found in gravel, as it is hard, chemically inert, and lacks cleavage planes along which the rock easily splits. Most gravel particles consist of multiple mineral grains, since few rocks have mineral grains coarser than about 8 millimeters (0.31 in) in size. Exceptions include quartz veins , pegmatites , deep intrusions , and high-grade metamorphic rock . The rock fragments are rapidly rounded as they are transported by rivers , often within
84-526: A minor component, making up less than 1% of all sedimentary rock. Alluvial fans likely contain the largest accumulations of gravel in the geologic record. These include conglomerates of the Triassic basins of eastern North America and the New Red Sandstone of south Devon . [REDACTED] Media related to Gravel at Wikimedia Commons Rock fragment A rock fragment , in sedimentary geology,
105-479: Is a sand-sized particle or sand grain that is made up of multiple grains that are connected on the grain scale. These can include grains which are sand-sized themselves (a granitic rock fragment), or finer-grained materials ( shale fragments). This definition is used for QFR ternary diagrams , provenance analysis, and in the Folk classification scheme, mainly in sandstones. This article related to petrology
126-875: Is a loose aggregation of rock fragments . Gravel occurs naturally on Earth as a result of sedimentary and erosive geological processes; it is also produced in large quantities commercially as crushed stone . Gravel is classified by particle size range and includes size classes from granule - to boulder -sized fragments. In the Udden-Wentworth scale gravel is categorized into granular gravel (2–4 mm or 0.079–0.157 in) and pebble gravel (4–64 mm or 0.2–2.5 in). ISO 14688 grades gravels as fine, medium, and coarse, with ranges 2–6.3 mm (0.079–0.248 in) for fine and 20–63 mm (0.79–2.48 in) for coarse. One cubic metre of gravel typically weighs about 1,800 kg (4,000 lb), or one cubic yard weighs about 3,000 lb (1,400 kg). Gravel
147-414: Is an important commercial product, with a number of applications. Almost half of all gravel production is used as aggregate for concrete . Much of the rest is used for road construction, either in the road base or as the road surface (with or without asphalt or other binders.) Naturally occurring porous gravel deposits have a high hydraulic conductivity , making them important aquifers . Colloquially,
168-534: Is sometimes distinguished from rubble, which is loose rock particles in the same size range but angular in shape. The Udden-Wentworth scale , widely used by geologists in the US, defines granular gravel as particles with a size from 2 to 4 mm (0.079 to 0.157 in) and pebble gravel as particles with a size from 4 to 64 mm (0.16 to 2.52 in). This corresponds to all particles with sizes between coarse sand and cobbles . The U.S. Department of Agriculture and
189-405: Is widely and plentifully distributed, mostly as river deposits, river flood plains, and glacial deposits, so that environmental considerations and quality dictate whether alternatives, such as crushed stone , are more economical. Crushed stone is already displacing natural gravel in the eastern United States, and recycled gravel is also becoming increasingly important. The word gravel comes from
210-702: The Old French gravele or gravelle . Different varieties of gravel are distinguished by their composition, origin, and use cases. Types of gravel include: In locales where gravelly soil is predominant, plant life is generally more sparse. This is due to the inferior ability of gravels to retain moisture, as well as the corresponding paucity of mineral nutrients, since finer soils that contain such minerals are present in smaller amounts. Sediments containing over 30% gravel that become lithified into solid rock are termed conglomerate . Conglomerates are widely distributed in sedimentary rock of all ages, but usually as
231-817: The Soil Science Society of America define gravel as particles from 2 to 80 mm (0.079 to 3.150 in) in size, while the German scale (Atterburg) defines gravel as particles from 2 to 200 mm (0.079 to 7.874 in) in size. The U.S. Army Corps of Engineers defines gravel as particles under 3 in (76 mm) in size that are retained by a number 4 mesh, which has a mesh spacing of 4.76 mm (0.187 in). ISO 14688 for soil engineering grades gravels as fine, medium, and coarse with ranges 2 mm to 6.3 mm to 20 mm to 63 mm. The bulk density of gravel varies from 1,460 to 1,920 kg/m (2,460 to 3,240 lb/cu yd). Natural gravel has
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#1732855481274252-455: The 17th and 18th centuries. All memory of its position was lost, until it was rediscovered in the 1880s by Valentine Ball , a geologist who helped to create this map of Golconda mines. In his annotated English edition of gem merchant Jean-Baptiste Tavernier 's book Travels in India (1676), Ball notes that ruins of houses and mine workings could still be found at Kollur. In the 1960s, Kollur Mine
273-490: The U.S., with a total value of about $ 12.6 billion. Some 960 million tons of construction sand and gravel were produced. This greatly exceeds production of industrial sand and gravel (68 million tons), which is mostly sand rather than gravel. It is estimated that almost half of construction sand and gravel is used as aggregate for concrete . Other important uses include in road construction, as road base or in blacktop ; as construction fill; and in myriad minor uses. Gravel
294-433: The king also received 2% from sales and he was entitled to keep all diamonds weighing over 10 carats. Mining at Kollur was crude, labour-intensive, and dangerous. Miners wore loincloths , slept in huts covered with straw, and were often given food instead of money for wages. The pit walls had no timber supports and caved in after heavy rains, killing dozens of men at a time (women and children worked above ground). The area
315-483: The periphery of the embayment. It has been suggested that wind-formed ( aeolian ) gravel "megaripples" in Argentina have counterparts on the planet Mars . Gravel is a major basic raw material in construction . Sand is not usually distinguished from gravel in official statistics, but crushed stone is treated as a separate category. In 2020, sand and gravel together made up 23% of all industrial mineral production in
336-536: The term gravel is often used to describe a mixture of different size pieces of stone mixed with sand and possibly some clay. The American construction industry distinguishes between gravel (a natural material) and crushed stone (produced artificially by mechanical crushing of rock.) The technical definition of gravel varies by region and by area of application. Many geologists define gravel simply as loose rounded rock particles over 2 mm (0.079 in) in diameter, without specifying an upper size limit. Gravel
357-544: Was bounded to the east by an outcrop of the Nallamala Hills and to the north and west by a meander of the Krishna River . Most of the pits have since been filled up with scree , boulders , and eluvium from neighbouring hillsides. The Tavernier Blue diamond was purchased by Jean-Baptiste Tavernier from the Kollur Mine in the mid-17th century. King Louis XIV of France bought the diamond from Tavernier, but it
378-533: Was evacuated in the 2000s to make way for the Pulichinthala irrigation project and is submerged by 50 feet (15 m) of water for most of the year. The gravel - clay pits were a maximum depth of 4 metres (13 ft) due to the high water table . The diamond-bearing seam was approximately 1 foot (30 cm) thick. Alluvial workings covered an area 1.5 kilometres (0.93 mi) long and between 500 metres (0.31 mi) and 800 metres (0.50 mi) wide. It
399-469: Was one of the largest and most productive diamond mines on the Indian subcontinent . At the height of production, around 30,000 – 60,000 people worked there, including men, women, and children of all ages. Kollur itself had a population of around 100,000. Golconda mines were owned by the king, but operation was leased to diamond merchants, either foreigners or Indians of the goldsmith caste . As well as rent,
420-521: Was pinpointed more accurately as being 1.5 kilometres (0.93 mi) due north-east of Kollur village on the south bank of River Krishna at latitude 16° 43' N and longitude 80° 02' E, and extending for 1.5 kilometres (0.93 mi) all the way up to Pulichinthala village. [REDACTED] Media related to Kollur Mine at Wikimedia Commons 16°43′N 80°02′E / 16.717°N 80.033°E / 16.717; 80.033 Gravel Gravel ( / ˈ ɡ r æ v əl / )
441-1129: Was stolen during the French Revolution ; it reappeared and has been re-cut as the Hope Diamond . Other diamonds thought to have originated at Kollur include the Koh-i-Noor , the Great Mogul, the Wittelsbach-Graff , the Regent , the Daria-i-Noor , the Orlov , the Nizam , the Dresden Green , and the Nassak . Kollur Mine's location on the south bank of the Krishna River is indicated at latitude 16° 42' 30" N and longitude 80° 5' E on several maps created in
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