|
Chatoyancy
In gemology, chatoyancy ( ), or chatoyance or cat's eye effect, is an optical reflectance effect seen in certain gemstones, woods, and carbon fibre. Coined from the French "œil de chat", meaning "cat's eye", chatoyancy arises either from the fibrous structure of a material, as in tiger's eye quartz, or from fibrous inclusions or cavities within the stone, as in cat's eye chrysoberyl. Description The precipitates that cause chatoyance in chrysoberyl are the mineral rutile, composed mostly of titanium dioxide. Examined samples have yielded no evidence of tubes or fibres. The rutile precipitates all align perpendicularly with respect to cat's eye effect. It is reasoned that the lattice parameter of the rutile matches only one of the three orthorhombic crystal axes of the chrysoberyl, resulting in preferred alignment along that direction. The effect can be likened to the sheen off a spool of silk: The luminous streak of reflected light is always perpendicular to the direction o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiger's Eye
Tiger's eye (also called tiger eye) is a chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown colour and a silky lustre. As members of the quartz group, tiger's eye and the related blue-coloured mineral hawk's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered amphibole fibres that have mostly turned into limonite. Other forms of tiger's eye ''Tiger iron'' is an altered rock composed chiefly of tiger's eye, red jasper and black hematite. The undulating, contrasting bands of colour and lustre make for an attractive motif and it is mainly used for jewellery-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to knife hilts. Tiger iron is mined primarily in South Africa and Western Australia. Tiger's eye is composed chiefly of silicon dioxide () and is coloured mainly by iron oxide. The specific gravity ranges from 2.64 to 2.71. It is f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tigers-Eye
Tiger's eye (also called tiger eye) is a chatoyant gemstone that is usually a metamorphic rock with a golden to red-brown colour and a silky lustre. As members of the quartz group, tiger's eye and the related blue-coloured mineral hawk's eye gain their silky, lustrous appearance from the parallel intergrowth of quartz crystals and altered amphibole fibres that have mostly turned into limonite. Other forms of tiger's eye ''Tiger iron'' is an altered rock composed chiefly of tiger's eye, red jasper and black hematite. The undulating, contrasting bands of colour and lustre make for an attractive motif and it is mainly used for jewellery-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads to knife hilts. Tiger iron is mined primarily in South Africa and Western Australia. Tiger's eye is composed chiefly of silicon dioxide () and is coloured mainly by iron oxide. The specific gravity ranges from 2.64 to 2.71. It is f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenite (mineral)
Selenite, satin spar, desert rose, gypsum flower are crystal habit varieties of the mineral gypsum. All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfate dihydrate (meaning that it has two molecules of water), with the chemical formula CaSO4·2H2O. Selenite contains no significant selenium – The similar names both derive from Greek ( 'Moon') Some of the largest crystals ever found are of selenite, the largest specimen found in the Naica Mine's Cave of the Crystals being 12 metres long and weighing 55 tons. History and etymology "Selenite" is mostly synonymous with gypsum, but from the 15th century, it has named the transparent variety that occurs in crystals or crystalline masses. The name derives through Middle English from Latin , ultimately from Greek (, ). It got this name because people historically believed the mineral waxed and waned with the cycles of the Moon. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labradorite
Labradorite (( Ca, Na)( Al, Si)4 O8) is a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect ( schiller). Labradorite is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573 and twinning is common. As with all plagioclase members, the crystal system is triclinic, and three directions of cleavage are present, two of which are nearly at right angles and are more obvious, being of good to perfect quality (while the third direction is poor). It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, as well as in anorthosites. Occurrence The geological type area for labradorite is Paul's Island near the town of Nain in Labrador, Canada. It has also been r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoxy
Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called ''epoxy''. The IUPAC name for an epoxide group is an oxirane. Epoxy resins may be reacted (cross-linked) either with themselves through catalytic homopolymerisation, or with a wide range of co-reactants including polyfunctional amines, acids (and acid anhydrides), phenols, alcohols and thiols (usually called mercaptans). These co-reactants are often referred to as hardeners or curatives, and the cross-linking reaction is commonly referred to as curing. Reaction of polyepoxides with themselves or with polyfunctional hardeners forms a thermosetting polymer, often with favorable mechanical properties and high thermal and chemical resistance. Epoxy has a wide range of applications, including metal coatings, composites, use in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wood Grain
Wood grain is the longitudinal arrangement of wood fibers or the pattern resulting from such an arrangement. Definition and meanings R. Bruce Hoadley wrote that ''grain'' is a "confusingly versatile term" with numerous different uses, including the direction of the wood cells (e.g., ''straight grain'', ''spiral grain''), surface appearance or figure, growth-ring placement (e.g., ''vertical grain''), plane of the cut (e.g., ''end grain''), rate of growth (e.g., ''narrow grain''), and relative cell size (e.g., ''open grain'').Hoadley, R. Bruce. "Glossary." ''Understanding Wood: A Craftsman's Guide to Wood Technology''. Newtown, Conn.: Taunton, 1980. 265. Print. Physical aspects Perhaps the most important physical aspect of wood grain in woodworking is the grain direction or slope (e.g. against the grain). The two basic categories of grain are straight and cross grain. Straight grain runs parallel to the longitudinal axis of the piece. Cross grain deviates from the longitudinal a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bird's Eye Figure
Bird's eye is a type of figure that occurs within several kinds of wood, most notably in hard maple. It has a distinctive pattern that resembles tiny, swirling eyes disrupting the smooth lines of grain. It is somewhat reminiscent of a burl, but it is quite different: the small knots that make the burl are missing. It is not known what causes the phenomenon. Research into the cultivation of bird's eye maple has so far discounted the theories that it is caused by pecking birds deforming the wood grain or that an infecting fungus makes it twist. However, no one has demonstrated a complete understanding of any combination of climate, soil, tree variety, insects, viruses or genetic mutation that may produce the effect. Bird's eye maple is most often found in ''Acer saccharum'' (sugar maple), but millers also find bird's eye figure in red maple, white ash, Cuban mahogany, American beech, black walnut, and yellow birch. Trees that grow in the Great Lakes region of Canada and the Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burl
A burl (American English) or burr (British English) is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds. Burl formation is typically a result of some form of stress such as an injury or a viral or fungal infection. Burls yield a very peculiar and highly figured wood sought after in woodworking, and some items may reach high prices on the wood market. Poaching of burl specimens and damaging the trees in the process poses a problem in some areas. Description A burl results from a tree undergoing some form of stress. It may be caused by an injury, virus or fungus. Most burls grow beneath the ground, attached to the roots as a type of malignancy that is generally not discovered until the tree dies or falls over. Such burls sometimes appear as groups of bulbous protrusions connected by a system of rope-like roots. Almost all burl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanmu
Nanmu () is a precious wood that is unique to China and South Asia, and was historically used for boat building, architectural woodworking, furniture and sculptural carving in China. The Ming Dynasty-era writings indicate this wood as superior durable softwood. A recent excavation of a tomb in Lija village in Jing'an County, Jiangxi Province, found 47 coffins made of nanmu wood that are reported to be about 2500 years old, dating back to the Eastern Zhou Dynasty period and belongs to the Dongyi State of Xu. The trees that produce nanmu wood are evergreens that have long, straight trunks which grows to 35 meters in height and one meter in diameter. More than 30 varieties exist, which are found south of the Yangtze River. There are also nanmu trees on Hainan Island and in Vietnam. Yangmu nanmu is found in Sichuan. Zinan nanmu is found in southeast and south central China. Zinanmu nanmu is found in Jiangsu, Anhui, Zhenjiang. Zhennan nanmu is found in Guizhou and Sichuan. The finest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardwood
Hardwood is wood from dicot trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen. Hardwood (which comes from angiosperm trees) contrasts with softwood (which is from gymnosperm trees). Characteristics Hardwoods are produced by angiosperm trees that reproduce by flowers, and have broad leaves. Many species are deciduous. Those of temperate regions lose their leaves every autumn as temperatures fall and are dormant in the winter, but those of tropical regions may shed their leaves in response to seasonal or sporadic periods of drought. Hardwood from deciduous species, such as oak, normally shows annual growth rings, but these may be absent in some tropical hardwoods. Hardwoods have a more complex structure than softwoods and are often much slower growing as a result. The dominant feature separating "hardwoods" from softwoods is the presence o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquamarine (gemstone)
Aquamarine is a pale-blue to light-green variety of beryl. The color of aquamarine can be changed by heat. Aquamarine has a chemical composition of Be3Al2Si6O18, also containing Fe2+. It has a hardness of 7.5 to 8. Aquamarine contains no or few noticeable inclusions but it can have inclusions like mica, hematite, or salt-water. Aquamarine is a common gemstone. However, there is a rarer deep blue variant called maxixe, but its color can fade due to sunlight. The color of maxixe is caused by NO3. Dark-blue maxixe color can be produced in green, pink or yellow beryl by irradiating it with high-energy radiation (gamma rays, neutrons or even X-rays). Name and etymology The name ''aquamarine'' comes from ''aqua'' (), and ''marine'', deriving from ''marina'' (). The word ''aquamarine'' was first used in the year 1677. The word ''aquamarine'' has been used as a modifier for other minerals like aquamarine tourmaline, aquamarine emerald, aquamarine chrysolite, aquamarine sapphire, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapolite
The scapolites (Gr. σκάπος, rod, and λίθος, stone) are a group of rock-forming silicate minerals composed of aluminium, calcium, and sodium silicate with chlorine, carbonate and sulfate. The two endmembers are meionite () and marialite (). Silvialite is also a recognized member of the group. Properties The group is an isomorphous mixture of the meionite and marialite endmembers. The tetragonal crystals are hemihedral with parallel faces (like scheelite), and at times of considerable size. They are distinct and usually have the form of square columns, some cleavages parallel to the prism-faces. Crystals are usually white or greyish-white and opaque, though meionite is found as colorless glassy crystals in the ejected limestone blocks of Monte Somma, Vesuvius. The hardness is 5–6, and the specific gravity varies with the chemical composition between 2.7 (meionite) and 2.5 (marialite). The scapolites are especially liable to alteration by weathering processes, wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Nanmu")
