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Topic: Conchoidal fracture

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Cleavage

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	Conchoidal fracture - Wikipedia, the free encyclopedia
		Conchoidal fractures often result in a curved breakage surface that resembles the rippling, gradual curves of a mussel shell; the word "conchoid" is derived from the word for this animal.
		They are defined in contrast to the faceted fractures often seen in single crystals such as semiconductor wafers and gemstones, and the high-energy ductile fracture surfaces desirable in most structural applications.
		Such fractures form the basis of flint knapping, since the shape of the broken surface is controlled only by the stresses applied, and not by some preferred orientation of the material.
	en.wikipedia.org /wiki/Conchoidal_fracture (300 words)

	Mineral Properties: Cleavage, Fracture, and Parting
		If fracture marks are present on a crystal in addition to a cleaved plane, the "cleaved" surface is usually the result of parting, not cleavage.
		Cleavage and fracture differ in that cleavage is the break of a crystal face where a new face (resulting in a smooth plane) is formed, whereas fracture is the "chipping" of a mineral.
		An good illustration of a conchoidal fracture is a large chip in a piece of glass.
	www.minerals.net /resource/property/cleavage.htm (1329 words)

	cleavage and fracture and parting and hackly fracture and splintery fracture and conchoidal and subconchoidal and ...
		Fracture happens to minerals that are roughly equal in bonding strength throughout the whole.
		Conchoidal fracture is the breaking in a semi-circular or smooth, curved surface that gives the appearance of a seashell or conch.
		Subconchoidal fracture is somewhere between conchoidal and even fracture, where even fracture means a smooth surface without the geometric sharpness of cleavage.
	www.willamette.edu /~blong/MoreWords/Cleavage.html (836 words)

	NationMaster - Encyclopedia: Rutile (Site not responding. Last check: 2007-10-09)
		Rutile has a sub-conchoidal fracture, is brittle, has a metallic-adamantine lustre, and is generally reddish brown but also sometimes yellowish, bluish, or violet.
		As a secondary mineral, rutile in the form of minute needles is of wide distribution in various sedimentary rocks, especially clays and slates.
		Rutile is the most stable form of titanium dioxide and is produced at the highest temperatures, with brookite being formed at lower temperatures and octahedrite being formed at still lower temperatures.
	www.nationmaster.com /encyclopedia/Rutile (1152 words)

	Colonial Opal - What is an Opal?
		Conchoidal fracture (Boulder opal and Yowah nut opal has good cleavage as it splits in mirror image).
		It has hardness ranging between 5-6.5, is brittle with a conchoidal fracture and some light varieties fluoresce white or yellow under long and short wave ultraviolet light.
		In this genetic model faults and fractures are only considered to have acted as a static passive conduit for the percolation of the silica-laden ground waters to depth through the rock mass.
	www.colonialopal.com.au /what.html (1038 words)

	Flintknapping, Obsidian
		This smooth, curved type of fracture surface allows for a predictable and controllable flake to be detached (fractured) from a larger piece of rock.
		Unlike obsidian, granite can't be flaked successfully by knapping because its crystals prevent conchoidal fracturing of the rock.
		Water absorption starts along cooling fractures in the glass and proceeds as concentric circles expanding away from the fractures toward the solid cores of unfractured rock.
	www.eskimo.com /~knapper/hotstuff.html (1750 words)

	definition of glass
		A hard, brittle, translucent, and commonly transparent substance, white or colored, having a conchoidal fracture, and made by fusing together sand or silica with lime, potash, soda, or lead oxide.
		It is used for window panes and mirrors, for articles of table and culinary use, for lenses, and various articles of ornament.
		Any substance having a peculiar glassy appearance, and a conchoidal fracture, and usually produced by fusion.
	www.brainydictionary.com /words/gl/glass169256.html (184 words)

	lithic
		A conchoidal fracture is one in which the fracture surfaces are curved.
		Due to conchoidal fracture properties, flakes and cores tend to have distinctive characteristics that vary with the flintknapping techniques used to produce them.
		Note that with any technique, because the interior surface of the flake and the corresponding surface of the core or unfinished tool were created by a single fracture, all of the characteristics of flakes also appear in an exact negative impression on the core or unfinished tool.
	www.utexas.edu /courses/denbow/labs/lithic2.htm (1036 words)

	NationMaster - Encyclopedia: Beryl (Site not responding. Last check: 2007-10-09)
		The hexagonal crystals of beryl may be very small or range to several meters in size.
		Beryl exhibits conchoidal fracture, has a hardness of 7.5-8, a specific gravity of 2.63-2.80.
		Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material.
	www.nationmaster.com /encyclopedia/Beryl (1498 words)

	Cannel coal, boghead coal, humic coal, and jet
		Tatsch (1980, p.33) notes that `cannel coal is a nonbanded, fl coal of bituminous rank with a conchoidal fracture' --- `it burns readily with a long smoky flame and is high in volatile constituents'.
		Cannel coal is massive and unlaminated, lending itself to carving, and breaks with a glassy conchoidal fracture.
		Van Krevelen (1981) confirms that the sapropelic coals (cannel and boghead coals, p.59) are of dull lustre and conchoidal fracture, and a splinter of these coals can be ignited by a match.
	www.turnstone.ca /cannel.htm (1354 words)

	Olivine (Site not responding. Last check: 2007-10-09)
		Olivine crystal lizes in the orthorhombic system in somewhat flattened forms but may occur massive or granular.
		It has a conchoidal fracture and is rather brittle.
		The hardness of olivine is 6.5-7, its specific gravity is 3.27-3.37 and it has a vitreous lustre.
	www.serebella.com /encyclopedia/article-Olivine.html (300 words)

	fracture resources
		Fracture is a screensaver for OS X that creates a wide variety of fractal images.
		Fracture is a description of the way a mineral tends to break.
		A fracture is the separation of a body into two, or more, pieces under the action of stress.
	www.1800md.com /md/fracture.html (384 words)

	Book of Job and splintery fracture and hackly and conchoidal fracture and uneven fracture and Job 16
		His "bonding" is similar throughout, and the result of this is that parts can't be "shaved" or "peeled" off as in cleavage when the sharp separation knife is applied to him.
		A combination of the hackly and splintery fracture of Job is evident a few verses later.
		Grief is Job's emotional conchoidal fracture, grief which burrows deep into the surface of his life only to gouge him deeply, scar him irreparably, moon-out an already debilitated heart.
	www.willamette.edu /~blong/MoreWords/CleavageII.html (864 words)

	Mystery Rock : can anyone help identify it
		Garnet can have a conchoidal to sub-conchoidal = fracture, but since it has imperfect cleavage, it often has a brittle = fracture.
		Obviously it fractures in circular patterns as can be seen in one of the photos.
		Garnet can have a conchoidal to sub-conchoidal fracture, but since it has imperfect cleavage, it often has a brittle fracture.
	www.totalblowhole.com /new-414197-4330.html (1320 words)

	Obsidian
		Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic "conchoidal" fracture.
		This smooth, curved type of fracture surface occurs because of the near-absence of mineral crystals in the glass.
		The intersections of conchoidal fracture surfaces can be sharper than a razor.
	volcano.und.edu /vwdocs/vw_hyperexchange/obsidian.html (1542 words)

	From Caveman to Chemist: Stone Tools
		When struck, quartzite fractures conchoidally but these fractures may be interrupted by the fractures initially present in the rock.
		The conchoidal fracture is the basis for all flintknapping.
		If you have ever seen the fracture which results when a BB hits a glass window, you have seen the conchoidal fracture.
	www.cavemanchemistry.com /oldcave/projects/stone/index.html (1621 words)

	Rocks and Minerals Lab
		Fracture - irregular breakage not related to planes of weakness in the mineral.
		Conchoidal fracture produces curved breakage surfaces, such as would be seen on arrowheads or chipped glass.
		The rock fractures through the grains (rather than between the grains as it does in sandstone).
	www.gpc.edu /~pgore/geology/historical_lab/rocks_minerals.php (1984 words)

	Mineral Descriptions
		Occurs as stout, prismatic crystals; conchoidal fracture, dull on external faces, but brilliant fl on fresh surfaces; associated with magnetite; often radioactive.
		Orthorhombic; occurs as transparent vitreous grains in irregular masses, and as a microcrystalline crust enclosing dark green spinel; conchoidal fracture.
		Radiating prismatic crystals, glassy or grainy masses; conchoidal fracture; radioactive.
	www.bancroftdistrict.com /Tourism/mineral_description.php (1608 words)

	NEWS CORNER
		: yellow-orange fan-shaped intergrowth to 3mm, transparent to translucent, vitreous, white streak, brittle, conchoidal fracture.
		Blocky to prismatic XX to 2mm, grey to brown, transparent, vitreous, white streak, H=5.5, brittle, uneven conchoidal fracture.
		Orange-yellow to brown, prismatic XX to 1mm, translucent to transparent, vitreous, H=5, brittle, uneven fracture.
	www.koeln.netsurf.de /~w.steffens/news.htm (1248 words)

	Uwharries Lithics Conference: Dr. Randy Daniel and Morrow Mtn
		Although it can be knapped, it has a cleavage-like plane to it, which, as you know, inhibits a good conchoidal fracture.
		Rhyolite is made up primarily of quartz and feldspar with a high silica content which gives it a good conchoidal fracture.
		My guess is that the presence of phenocrysts hamper the quality of the conchoidal fracture.
	www.arch.dcr.state.nc.us /uwharrie/morrowmtn.html (1217 words)

	Here's how to make an arrowhead by flintknapping
		The best rock is somewhat brittle and uniform in texture and structure, lacking frost fractures, inclusions, or other flaws.
		These rock types, when struck with another rock, piece of antler, or bone, will fracture or break in a characteristic pattern called a conchoidal fracture.
		A new fire is built and allowed to burn out over a 24 hour period before digging up the heat treated pieces.
	www.farmersmarketonline.com /howto21.htm (681 words)

	Visionlearning Glossary
		A type of breakage that produces a smooth, curved surface.
		Conchoidal fracture occurs when a substance has uniform strength in all directions and no pre-existing planes of atomic weakness.
		This generally occurs in two types of substances: minerals like quartz whose atomic structure consists of equally strong bonds in all directions, and volcanic glass, called obsidian, which has no definitive crystal structure.
	www.visionlearning.com /library/glossary.php?a=C&l= (878 words)

	glass Quotes - Inspirational Quotes at Quotes-Zone.com
		Definition: A hard, brittle, translucent, and commonly transparent substance, white or colored, having a conchoidal fracture, and made by fusing together sand or silica with lime, potash, soda, or lead oxide.
		Definition: Any substance having a peculiar glassy appearance, and a conchoidal fracture, and usually produced by fusion.
		Definition: A vessel filled with running sand for measuring time; an hourglass; and hence, the time in which such a vessel is exhausted of its sand.
	www.quotes-zone.com /quotes/12/glass.php (253 words)

	Seslisozluk.com sesli sözlük ingilizce sözlük Türkçe sözlük Almanca sözlük Turkish dictionary English ...
		Transparent or opaque solid formed from sand fusion reactions Usually very hard and dense but can be fractured easily.
		A solid with the molecular structure of a liquid, strictly an extremely viscous liquid with many mechanical properties of a solid.
		A hard, brittle, translucent, and commonly transparent substance, white or colored, having a conchoidal fracture, and made by fusing together sand or silica with lime, potash, soda, or lead oxide It is used for window panes and mirrors, for articles of table and culinary use, for lenses, and various articles of ornament.
	www.seslisozluk.com /?word=glass (953 words)

	glass - meaning and definition of the word. (Site not responding. Last check: 2007-10-09)
		You can double click on any word to find it's meaning when you see the help cursor.
		t.] A hard, brittle, translucent, and commonly transparent substance, white or colored, having a conchoidal fracture, and made by fusing together sand or silica with lime, potash, soda, or lead oxide.
		t.] Any substance having a peculiar glassy appearance, and a conchoidal fracture, and usually produced by fusion.
	dictionary.blintz.com /dictionary/glass (213 words)

	GemRocks: Coal
		Anthracite (=hard coal) - fl, typically with a high, almost metallic, luster and a conchoidal fracture.
		In addition, some fracture surfaces exhibit a peacock-like play of colors that resembles those exhibited by films of oil on water.
		Cannel coal appears homogeneous macroscopically despite the fact that it consists largely of spores that can be seen by using even a low-power microscope.
	www.cst.cmich.edu /users/dietr1rv/coal.htm (854 words)

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