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Topic: Crystal habit

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	Accelrys > Case Studies > Crystal Morphology Tools used in the Fight Against Malaria
		The prediction of crystal habit, the analysis of surface structure, and the design of additives is leading to pigments which show greatly improved performance expressed by a higher color strength, improved color shades, and a better color saturation.
		The [011] crystal face was identified as a dominant crystal face and analyzed in detail.
		This computational study demonstrated how the prediction of the crystal habit, the analysis of the surface structure and the design of additives is leading to pigments which show greatly improved performance expressed by a higher color strength, a more yellowish color shade and a better color saturation.
	www.accelrys.com /reference/cases/studies/perylenered.html (305 words)

	Mineral - New World Encyclopedia Preview
		The crystal structure of a mineral is the orderly, geometric arrangement of atoms or ions in the mineral's internal structure.
		There are 14 basic crystal lattice arrangements of atoms in three dimensions, and these are referred to as the 14 "Bravais lattices." Each of these lattices can be classified into one of the six "crystal systems." All currently recognized crystal structures fit into one Bravais lattice and one crystal system.
		The typical, outward appearance of a mineral is called the "crystal habit." Some crystal habits are distinctive of certain minerals, but in most cases, a mineral exhibits a variety of habits that are influenced by the growth conditions of the crystals.
	www.newworldencyclopedia.org /preview/Mineral (2156 words)

	Crystal Growing K-12 Experiments for Lesson Plans & Science Fair Projects
		Which crystal structure the fluid will form depends on the chemistry of the fluid, the conditions under which it is being solidified, and also on the ambient pressure.
		A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way; which is periodically repeated in three dimensions on a lattice.
		Crystal structures can be divided into 32 classes, or point groups, according to the number of rotational axes and reflection planes they exhibit that leave the crystal structure unchanged.
	www.juliantrubin.com /encyclopedia/chemistry/crystal.html (2408 words)

	CRYSTAL HABIT
		Crystal habit is a description of the shapes and aggregates that a certain mineral is likely to form.
		If a dome or sphenoid is on the side of a crystal it might be confused with two of the four faces of a prism (look for similar faces on the other side of the crystal axes).
		The scalahedron is a general term for three crystal forms differentiated by the symmetry of the prominent axis.
	mineral.galleries.com /minerals/crystal.htm (0 words)

	[No title]
		Columnar -- a crystal habit that is a subparallel arrangement of slender elongate individual crystals.
		Monoclinic -- a crystal system in which the three crystallographic axes (a, b, c) are of unequal length and a:b = b:c = 90 degrees; a:c = 90 degrees.
		Orthorhombic -- a crystal system in which the three crystallographic axes (a, b, c) are unequal in length (a=b=c) and a, b, and c are at 90 degrees to each other.
	www.state.ar.us /agc/glossary.txt (1452 words)

	Crystal Form, Zones, & Habit
		In the monoclinic, triclinic, and orthorhombic crystal systems, the form {111} is a general form because in these systems faces of this form will intersect the a, b, and c axes at different lengths because the unit lengths are different on each axis.
		In crystals of higher symmetry, where two or more of the axes have equal length, a general form must intersect the equal length axes at different multiples of the unit length.
		Although a crystal structure is an ordered arrangement of atoms on a lattice, as we have seen, the order may be different along different directions in the crystal.
	www.tulane.edu /~sanelson/eens211/forms_zones_habit.htm (0 words)

	Methods of modifying crystal habit invention
		The modification in crystal habit is attributable to a preferential adsorption mechanism of the crystal growth inhibitor to a fast growing crystal face of the compound.
		Crystal habit and the crystal size distribution are two key physical properties involved in the formulation of solid dosage forms.
		[0017] One embodiment of the invention is a co-precipitate of a crystalline compound and a crystal growth inhibitor formed by contacting a solvent containing a compound and a crystal growth inhibitor, with an anti-solvent to extract the solvent from a co-precipitate of the compound and the crystal growth inhibitor.
	www.freshpatents.com /Methods-of-modifying-crystal-habit-dt20060413ptan20060078573.php (1735 words)

	Effect of Impurities and additives on Crystal Growth
		Crystal habit or morphology is often used quite loosely to describe the shape and aspect ratio of crystals.
		Comparison of crystallization from pure and impure solutions may indicate whether or not significant habit modification is caused by the impurities in the test solutions.
		Certain crystal habits are disliked in commercial crystals because they give the crystalline mass a poor appearance; others make the product prone to caking, induce poor flow characteristics or give rise to difficulties in the handling or packaging of the material.
	www.lut.fi /~hhatakka/docit/impure.html (1847 words)

	Science of Minerals
		Depending on the number of degrees through which the crystal must be rotated to produce this effect, a crystal may look the same from 2, 3, 4, or 6 different positions; such a crystal is described as having n-fold symmetry (e.g.: "2-fold symmetry") along that axis of rotation.
		Crystal habit depends not only on atomic structure and crystal symmetry, but also on on the environment in which the crystals grew, and so a given mineral species may exhibit different crystal habits at different localities.
		occurs during crystal growth, and is thought to occur as a result of nucleation errors, due to the addition of a few atoms or ions in the wrong place on the surface of a growing crystal.
	www.utexas.edu /tmm/npl/mineralogy/Science_of_Minerals/index.htm (1692 words)

	College Geology Department, Physical Geology, mineralogy examples
		Crystal faces do not penetrate into the body of the crystal, whereas cleavages, as parallel sets of cracks, can.
		The microscopic crystals scatter the light in all directions, giving the sample a dull appearance.
		The crystals are large enough to be opaque.
	www.union.edu /PUBLIC/GEODEPT/COURSES/geo-10/mineral.htm (559 words)

	Control of form of crystal precipitation of aluminum hydroxide using cosolvents and varying caustic concentration - ...
		Disclosed is generally spherical aluminum hydroxide particles comprised of solid crystals of aluminum hydroxide, the crystals extending radially outwardly from a central core region and having a shape selected from lamellar and acicular, the particle density ranging from 0.3 to 2.5 gms/cc.
		Generally spherical aluminum hydroxide particles are formed comprised of solid crystals of aluminum hydroxide, the crystals extending radially outwardly from a central core region and having a shape selected from lamellar and acicular, the particle density ranging from 0.3 to 2.5 gms/cc.
		In accordance with one aspect of the invention, the habit of the crystals expressed as the axial ratio of diameter to length is dependent upon the concentration of the alkali metal hydroxide.
	www.freepatentsonline.com /4822593.html (3719 words)

	Physical Characteristics of Minerals
		Both the positioning of crystal faces in a mineral and the property of cleavage are derived from the crystalline structure of the species.
		The terminology used to describe crystal habit is not intended to replace the precise nomenclature of crystallography.
		Stalactitic or columnar crystal habit refers to the tall, tapered, columlike appearance of an icicle or a limestone stalactite.
	dave.ucsc.edu /myrtreia/physical_character.html (5718 words)

	Intro to Minerals: Crystal Class and System
		For example, crystals of the holomorphic class of the isometric system possess inversion symmetry, three 4-fold axes of rotational symmetry, the characteristic set of four 3-fold axes of rotational symmetry which is indicative of the isometric crystal system, six 2-fold axes of rotational symmetry, and nine different mirror planes.
		Crystals of the triclinic system may be said to possess only a 1-fold symmetry axis, which is equivalent to possessing no symmetry at all.
		The rhombic pyramidal crystal class is thus a member of the orthorhombic crystal system, the tetragonal pyramidal class is a member of the tetragonal crystal system, and the trigonal and hexagonal pyramidal classes are members of the rhombohedral (trigonal) and hexagonal divisions of the hexagonal crystal system respectively.
	dave.ucsc.edu /myrtreia/crystal.html (4278 words)

	Crystal habit - Definition, explanation
		Crystal habit may mislead the inexperienced as a mineral's crystal system can be hidden or disguised.
		Factors influencing a crystal's habit include: a combination of two or more formss; trace impurities present during growth; crystal twinning and growth conditions (i.e., heat, pressure, space).
		Some habits of a mineral are unique to its variety and locality: For example, while most sapphires form elongate barrel-shaped crystals, those found in Montana form stout tabular crystals.
	www.calsky.com /lexikon/en/txt/c/cr/crystal_habit.php (0 words)

	Optimizing the Crystal Size and Habit of â-Sitosterol in Suspension
		Crystals with a median crystal length of ~23 μm were achieved with a low cooling temperature (<10°C); however, a fairly large number of crystals over 50 μm appeared.
		The rate-limiting steps for crystal growth are generally considered to be the rate of transport of growth units to the crystal surface (diffusion-controlled) and/or integration into the crystal lattice.
		A minor factor influencing the nucleation and crystal growth as the temperature decreases is the resulting increase in the viscosity of the oil, causing diminished molecular movement.
	www.aapspharmscitech.org /view.asp?art=pt040344&pdf=yes (3890 words)

	Mineral Kingdom - Crystalinks
		A crystal structure is the orderly geometric spatial arrangement of atoms in the internal structure of a mineral.
		This crystal structure is based on regular internal atomic or ionic arrangement that is often visible as the mineral form.
		Similarly, some minerals have different chemical compositions, but the same crystal structure: for example, halite (made from sodium and chlorine), galena (made from lead and sulfur) and periclase (made from magnesium and oxygen) all share the same cubic crystal structure.
	www.crystalinks.com /mineral.html (1247 words)

	Detroit Salt Company
		Hopper crystals form due to the disparity of growth rates between the crystal edges and the crystal faces.
		In fact, the crystals form so fast and so well in some evaporative lakes that mineral dealers are using their imaginations to enhance their inventory.
		Crystal Habits are predominantly cubes and in massive sedimentary beds, but also granular, fibrous and compact.
	www.detroitsalt.com /salt-rock.htm (547 words)

	Habit & Form
		Crystals to two centimetres diameter and greater were found when Liroconite was first discovered in Cornwall (1780-1790).
		In 1808 the largest known crystal, reaching 3.5cm, was added to the famous Rashliegh collection.
		Liroconite crystals have an unusual shape, and are composed of the sides of a four faced prism, and four faces of two monoclinic domes.
	liroconite.britishrocks.com /Habit___Form/habit___form.html (419 words)

	Crystal Habit
		The term "crystal habit" is used to identify the shape, size and appearance of a crystal's unique growth characteristics, or "Crystal Forms".
		Crystal habits are useful in communicating what specimens of a particular mineral would, or should look like.
		Most gemstone crystals are not found as perfectly formed single crystals but are found as aggregates of several crystals grown together in one mass.
	www.khulsey.com /jewelry/crystal_habit.html (0 words)

	Gemstones :: Crystal Habit
		The many terms used by mineralogists to describe crystal habits are useful in communicating what specimens of a particular mineral often look like.
		Crystal habit may mislead the inexperienced as a mineral's crystal system can be hidden or disguised.
		Some habits of a mineral are unique to its variety and locality: For example, while most sapphires form elongate barrel-shaped crystals, those found in Montana form stout tabular crystals.
	www.bleedingedge.net /Gemstones/Crystal-Habit.aspx (240 words)

	Diamonds \| American Museum of Natural History
		Using this cubic form and its highly symmetrical arrangement of atoms, diamond crystals can develop in a variety of different shapes known as "crystal habits." The octahedron, or eight-sided shape that we associate with diamonds is its most common crystal habit.
		All of these shapes are manifestations of the cubic crystal system to which the mineral diamond belongs.
		Two exceptions are the flat form called a macle, which is actually a composite crystal, and etched crystals, which have rounded surfaces and, sometimes, elongated shapes.
	www.amnh.org /exhibitions/diamonds/structure.html (308 words)

	myelections.com Crystal
		A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.
		Under ideal conditions, the result may be a single crystal, where all of the atoms in the solid fit into the same crystal lattice or crystal structure but, generally, many crystals form simultaneously during solidification, leading to a polycrystalline solid.
		The shape of these crystals is dependent on the types of molecular bonds between the atoms to determine the structure, as well as on the conditions under which they formed.
	www.myelections.com (0 words)

	GemResearch Swisslab (GRS) Specializing in Origin Determination of Fine Rubies and Sapphires (Site not responding. Last check: )
		The basic habit of corundum consists of a small number of significant crystal forms: the basal pinacoid, the hexagonal prism, the positive rhombohedron, and the negative rhombohedron, as well as different hexagonal dipyramids.
		The crystal habit of Mong Hsu rubies consists of two hexagonal dipyramids, "n" (2 2 -4 3) and "omega" (14 14 -28 3), the basal pinacoid "c" (0 0 0 1), and the positive rhombohedron "r" (1 0 -1 1).
		The crystal drawn on the left is dominated by "omega" and "c" faces, with a subordinate "r" plane.
	www.gemresearch.ch /monghsu/crystal1.htm (146 words)

	"A33C-1020" in fm06
		Most satellite retrieval algorithms typically use IR observations to determine the phase (ice or water) and in the case of ice clouds assume a fixed crystal habit (or fixed mixture of habits).
		We have generated a look-up table of MISR and MODIS reflectance as a function of optical depth, effective radius, crystal habit, and solar and satellite geometry.
		Differences in optical depth and effective radius are seen as a function of retrieved crystal habit.
	www.agu.org /cgi-bin/wais?hh=A33C-1020 (0 words)

	Solubility, Polymorphism, Crystallinity, and Crystal Habit of Acetaminophen and Ibuprofen by Initial Solvent Screening ...
		The crystal habit of an API also has profound effects on the rate at which the API can be processed in filtering, washing, and drying, and the success of the API in powder flow, blending, direct compaction, roller compaction, wet granulation, and dissolution rate (16–19).
		Because solubility, polymorphism, crystallinity, and crystal habit are all solvent dependent, solvent screening is of fundamental and foremost importance to many chemical process industries, especially the pharmaceutical industry (4, 20–22).
		Solubility, polymorphism, crystallinity, and crystal habit of acetaminophen and racemic (+/-)-ibuprofen were determined by initial screening of 23 solvents for scale-up.
	www.pharmtech.com /pharmtech/article/articleDetail.jsp?id=378746 (621 words)

	CRYSTAL_LAB
		Crystal Lab should be able to display crystals in three dimensions, and allow the user to create and manipulate crystals in three dimensions.
		Users should be able to move the light source close to or far from the crystal, and should be able to scroll through the space between the light source and the crystal.
		Crystal Lab should be able to display areas of water drops, and allow the user to specify, size, and density.
	cs.unm.edu /~joel/CrystalLab/CrystalLab.html (1090 words)

	Blog All Title - Post details: Technical, Trade, Mineralogical, New Age Terminology
		Wand crystals or minerals deliberately cut and polished into a specific shape, usually with a single or double point at one or both of the ends.
		Self Healed a crystal which has broken away from the matrix or main cluster and then continued to grow by forming a selection of smaller crystal growths.
		The New age terminology is very new and tends to describe crystals and minerals from an esoteric and subjective point of view.
	globalcrystals.com /blog/index.php/all/2006/08/25/technical_trade_mineralogical_new_age_te (890 words)

	Crystal Habit Changes and Dosage Form Performance (Site not responding. Last check: )
		Habit describes the external shape of a crystal, whereas polymorphic state refers to the definite arrangement of molecules inside the crystal lattice.
		In addition, changes in crystal habit accompanied with or without polymorphic transformation during processing or storage can lead to serious implications of physical stability in dosage forms.
		Therefore to minimize variations in raw material characteristics, to ensure reproducibility of results during preformulation, and to correctly judge the cause of instability and poor performance of a dosage form, it is essential to recognize the importance of changes in crystal surface appearance and habit of pharmaceutical powders.
	www.dekker.com /sdek/59582815-52420431/abstract~db=enc~content=a713491632~words= (413 words)

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