"Talc Talc or talcum is a clay mineral composed of hydrated magnesium silicate with the chemical formula HMg(SiO) or MgSiO(OH). In loose form, it is (in ratio with or without corn starch) one of the most widely used substances known as baby powder. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage, and the folia are not elastic, although slightly flexible. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 1 as the hardness of talc. Talc can easily be scratched by a fingernail. Talc"
"and the radioisotopes present a significant health and ecological hazard in the environment. Caesium is the softest element (it has a hardness of 0.2 Mohs). It is a very ductile, pale metal, which darkens in the presence of trace amounts of oxygen. When in the presence of mineral oil (where it is best kept during transport), it loses its metallic lustre and takes on a duller, grey appearance. It has a melting point of , making it one of the few elemental metals that are liquid near room temperature. Mercury is the only elemental metal with a known melting point"
"Y, and pale red when viewed along Z. Pleochroism should not be present if the mineral is colourless. It is not fluorescent. Köttigite is soft, with Mohs hardness only to 3, even softer than calcite, which has a hardness of 3. It is also fairly light, with specific gravity 3.33. Because of its sheetlike structure it has perfect cleavage perpendicular to the b axis; it is flexible, and has a fibrous fracture giving it a silky lustre on cleavage surfaces. It is soluble in acids. It is formed by the alteration of smaltite (Co,Fe,Ni)As and sphalerite ZnS. in oxidized zones"
"any mineral. Its mean refractive index is 3.08 (sodium light wavelengths), versus the indices for diamond and the non-mineral gallium(III) arsenide (GaAs), which are 2.42 and 3.93, respectively. The hardness of cinnabar is 2.0–2.5 on the Mohs scale, and its specific gravity 8.1. Structurally, cinnabar belongs to the trigonal crystal system. It occurs as thick tabular or slender prismatic crystals or as granular to massive incrustations. Crystal twinning occurs as simple contact twins. Note, mercury(II) sulfide, HgS, adopts the cinnabar structure described, and one additional structure, i.e. it is dimorphous. Cinnabar is the more stable form, and is a structure"
"Y= pale yellowish green, pale bluish green or yellow-green; Z= pale yellowish green or olive-yellow. X is parallel to the b crystal axis and Z is inclined to the c crystal axis at an angle of 28.5°. It is not fluorescent. Vivianite is a soft mineral, with Mohs hardness only to 2, and specific gravity 2.7. It splits easily, with perfect cleavage perpendicular to the b crystal axis, due to the sheet-like structure of the mineral. It is sectile, with a fibrous fracture, and thin laminae parallel to the cleavage plane are flexible. It is easily soluble in acids. It"
"a silvery-grey metal with a Mohs hardness of 5.5, and a standard atomic weight of 95.95 g/mol. It has a melting point of ; of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten, and carbon have higher melting points. It has one of the lowest coefficients of thermal expansion among commercially used metals. The tensile strength of molybdenum wires increases about 3 times, from about 10 to 30 GPa, when their diameter decreases from ~50–100 nm to 10 nm. Molybdenum is a transition metal with an electronegativity of 2.16 on the Pauling scale. It does not visibly react with"
"Monazite Monazite is a reddish-brown phosphate mineral containing rare-earth metals. It occurs usually in small isolated crystals. It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense, about 4.6 to 5.7 g/cm. There are at least four different kinds of monazite, depending on relative elemental composition of the mineral: The elements in parentheses are listed in the order of their relative proportion within the mineral: lanthanum is the most common rare-earth element in monazite-(La), and so forth. Silica (SiO) is present in trace amounts, as well as small amounts of uranium"
"Emerald Emerald is a gemstone and a variety of the mineral beryl (BeAl(SiO)) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor. Emerald is a cyclosilicate. The word ""emerald"" is derived (via and ), from Vulgar Latin: ""esmaralda""/""esmaraldus"", a variant of Latin ""smaragdus"", which originated in (smaragdos; ""green gem""). Emeralds, like all colored gemstones, are graded using four basic parameters–the four ""C""s of connoisseurship: ""color"", ""clarity,"" ""cut"" and ""carat weight"". Normally, in the"
"the softest known substances, and diamond, the hardest naturally occurring substance. It bonds readily with other small atoms, including other carbon atoms, and is capable of forming multiple stable covalent bonds with suitable multivalent atoms. Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements. At atmospheric pressure it has no melting point, as its triple point is at and , so it sublimes at about 3,900 K. Graphite is much more reactive than diamond at standard conditions, despite being more thermodynamically stable,"
"Mohs scale of mineral hardness The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by seeing which minerals can visibly scratch others is, however, of great antiquity, having been mentioned by Theophrastus in his treatise ""On Stones"", c. 300 BC, followed by Pliny the Elder in his ""Naturalis Historia"", c."
"mineral does not fluoresce in ultraviolet light. Cleavage is perfect parallel to (100). Crystals of ianbruceite are flexible and deform plastically. The mineral is very soft, with Mohs hardness only 1, the same as talc. Measurements of the specific gravity have not been reported, but from the formula and the cell dimensions it has been calculated as 3.197. It is insoluble in dilute acid, which distinguishes it from hydrozincite and aragonite, which are also supergene minerals that form white crusts. The loosely bound water between the layers is easily lost, so the mineral may effloresce. It also readily absorbs alcohol."
"in turn derives from the Sanskrit ""Kuruvinda"". Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost every other mineral. It is commonly used as an abrasive on everything from sandpaper to large tools used in machining metals, plastics, and wood. Some emery is a mix of corundum and other substances, and the mix is less abrasive, with an average Mohs hardness of 8.0. In addition to its hardness, corundum has a density of , which is unusually high for a transparent mineral composed of the low-atomic mass elements aluminium and"
"has also been reported from Salamanca Province, Spain; the Organullo Mining District of Salta Province, Argentina; and the Delamar Mountains of Lincoln County, Nevada, US. Mohite Mohite is a copper tin sulfide mineral with the chemical formula CuSnS. It is colored greenish gray and leaves a gray streak. It is opaque and has metallic luster. Its crystal system is triclinic pedial. It is rated 4 on the Mohs Scale and has a specific gravity of 4.86. Mohite was first described in 1982 for an occurrence in the Chatkal-Kuramin Mountains of eastern Uzbekistan. It was named after Günter Harald Moh (1929–1993),"
"(""proper"", ""unalterable"", ""unbreakable"") and sometimes called adamant, diamond is the hardest known naturally occurring material, scoring 10 on the Mohs scale of mineral hardness. Diamond is extremely strong owing to the structure of its carbon atoms, where each carbon atom has four neighbors joined to it with covalent bonds. The material boron nitride, when in a form structurally identical to diamond (zincblende structure), is nearly as hard as diamond; a currently hypothetical material, beta carbon nitride, may also be as hard or harder in one form. It has been shown that some diamond aggregates having nanometer grain size are harder"
"as waterhouseite. Waterhouseite Waterhouseite, Mn(PO)(OH), is a hydroxy manganese phosphate mineral. It is a medium-soft, brittle mineral occurring in pseudo-orthorhombic monoclinic bladed crystals and orange-brown to dark brown in color. Waterhouseite is on the softer side with a Mohs hardness of 4, has a specific gravity of 3.5 and a yellowish-brown streak. It is named after Frederick George Waterhouse, first director of the South Australian Museum, as well as recognizes the work Waterhouse Club has done in support of the South Australian Museum. Waterhouseite occurs in divergent sprays of bladed crystals up to 1mm in length and 20 micrometers in"
"incorporates additional substances that may fall between levels: Comparison between hardness (Mohs) and hardness (Vickers): Mohs scale of mineral hardness The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by seeing which minerals can visibly scratch others is, however, of great antiquity, having been mentioned by Theophrastus in his treatise"
"The mineral is brittle and breaks with a subconchoidal to uneven fracture. It is quite soft, with Mohs hardness 3 to , just a little harder than calcite. The hardness is slightly greater on crystal surfaces. It is a heavy mineral, with specific gravity 5.9, because of the lead content. It is readily soluble in acids. Orthorhombic crystals (and triclinic and monoclinic crystals) have two directions in which light travels with zero birefringence; these directions are called the optic axes, and the crystal is said to be biaxial. The speed of a ray of light travelling through the crystal differs"
"Mohite Mohite is a copper tin sulfide mineral with the chemical formula CuSnS. It is colored greenish gray and leaves a gray streak. It is opaque and has metallic luster. Its crystal system is triclinic pedial. It is rated 4 on the Mohs Scale and has a specific gravity of 4.86. Mohite was first described in 1982 for an occurrence in the Chatkal-Kuramin Mountains of eastern Uzbekistan. It was named after Günter Harald Moh (1929–1993), University of Heidelberg. It is of hydrothermal origin and occurs associated with tetrahedrite, famatinite, kuramite, mawsonite and emplectite in the type locality in Uzbekistan. It"
"poor cleavage in one direction parallel to the c crystal axis and traces of cleavage in a direction perpendicular to both the a and the b crystal axes. Twinning is uncertain. The mineral has a Mohs hardness of to 6, between apatite and feldspar. This is the same hardness as anatase and a little less than that of rutile (6 to ). The specific gravity is 4.08 to 4.18, between that of anatase at 3.9 and rutile at 4.2. Brookite is an accessory mineral in alpine veins in gneiss and schist; it is also a common detrital mineral. Associated minerals"
"is similar to diamond in several important respects: it is transparent and hard (9–9.5 on the Mohs scale, compared to 10 for diamond), with a refractive index between 2.65 and 2.69 (compared to 2.42 for diamond). Moissanite is somewhat harder than common cubic zirconia. Unlike diamond, moissanite can be strongly birefringent. For this reason, moissanite jewels are cut along the optic axis of the crystal to minimize birefringent effects. It is lighter (density 3.21 g/cm vs. 3.53 g/cm), and much more resistant to heat than diamond. This results in a stone of higher luster, sharper facets, and good resilience. Loose"
"testing the resilience of certain flat panel display components (such as cover glass for LCDs or encapsulation for OLEDs). The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly. The samples of matter used by Mohs are all different minerals. Minerals are chemically pure solids found in nature. Rocks are made up of one or more minerals. As the hardest known naturally occurring substance when the scale was designed, diamonds are at the top of the scale. The hardness of a material is measured against the scale by"
"luster and is fairly transparent with a light-green to blue green color. Herbertsmithite has a Mohs hardness of between 3 and 3.5 and is known to have a brittle tenacity. The crystal's density has been calculated at 3.76 g/cm. Herbertsmithite, in a pure synthetic form, was discovered in 2012 to be able to exhibit the properties of a quantum spin liquid, a generalized form of strongly correlated quantum spin liquid due to its Kagome lattice structure. Herbertsmithite is the first mineral known to exhibit this unique state of magnetism: it is neither a ferromagnet with mostly aligned magnetic particles, nor"
"stable metals; this is exceeded only by darmstadtium, roentgenium, and copernicium among the superheavy metals. The [Rg(HO)] cation is expected to be the softest among the metal cations. Due to relativistic stabilisation of the 7s subshell, roentgenium is expected to have a full s-subshell and a partially filled d-subshell, instead of the free s-electron and full d-subshell of copper, silver, and gold. On the group 12 transition metals (zinc, cadmium and mercury), Smith observed that, ""Textbook writers have always found difficulty in dealing with these elements."" There is an abrupt and significant reduction in physical metallic character from group 11"
"integrity, they are not considered ""scratches"" for the determination of a Mohs scale number. The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (10) is four times as hard as corundum. The table below shows the comparison with the absolute hardness measured by a sclerometer, with pictorial examples. On the Mohs scale, a streak plate (unglazed porcelain) has a hardness of approximately 7.0. Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale. The table below"
"Waterhouseite Waterhouseite, Mn(PO)(OH), is a hydroxy manganese phosphate mineral. It is a medium-soft, brittle mineral occurring in pseudo-orthorhombic monoclinic bladed crystals and orange-brown to dark brown in color. Waterhouseite is on the softer side with a Mohs hardness of 4, has a specific gravity of 3.5 and a yellowish-brown streak. It is named after Frederick George Waterhouse, first director of the South Australian Museum, as well as recognizes the work Waterhouse Club has done in support of the South Australian Museum. Waterhouseite occurs in divergent sprays of bladed crystals up to 1mm in length and 20 micrometers in thickness. It"
"or P2221. The structure is similar to that of hydrozincite. There are four formula units per unit cell (Z = 4) and the lengths of the sides of the unit cell are a = 15.724 Å, b = 6.256 Å and c = 5.427 Å. Brianyoungite is a soft mineral with Mohs hardness similar to halite, only 2 to according to some sources, but others say that the hardness is not determinable. It is fairly dense, with specific gravity 3.93 to 4.09, similar to that of celestine. Cleavage is perfect perpendicular to the a crystal axis (perfect on {100}) and"
"very soft metal with a Mohs hardness of 1.5; it can be scratched with a fingernail. It is quite malleable and somewhat ductile. The bulk modulus of lead—a measure of its ease of compressibility—is 45.8 GPa. In comparison, that of aluminium is 75.2 GPa; copper 137.8 GPa; and mild steel 160–169 GPa. Lead's tensile strength, at 12–17 MPa, is low (that of aluminium is 6 times higher, copper 10 times, and mild steel 15 times higher); it can be strengthened by adding small amounts of copper or antimony. The melting point of lead—at 327.5 °C (621.5 °F)—is very low compared"
"Caesium Caesium (IUPAC spelling) or cesium (American spelling) is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28.5 °C (83.3 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium. The most reactive of all metals, it is pyrophoric and reacts with water even at −116 °C (−177 °F). It is the least electronegative element, with a value of 0.79 on the Pauling scale. It"
"has Mohs hardness of 5 and a density of 2.1 g/cm. When it forms well developed crystals they are hairlike; very long, thin, and delicate. Mordenite’s molecular structure is a framework containing chains of five-membered rings of linked silicate and aluminate tetrahedra (four oxygen atoms arranged at the points of a triangular pyramid about a central silicon or aluminium atom). Its high ratio of silicon to aluminum atoms makes it more resistant to attack by acids than most other zeolites. Mordenite is one of the most abundant zeolites in altered volcanic deposits; it is found in volcanic rock such as"
"compensatory damages) against J&J, concluding that the company had suppressed evidence of asbestos in its products for more than four decades. Talc Talc or talcum is a clay mineral composed of hydrated magnesium silicate with the chemical formula HMg(SiO) or MgSiO(OH). In loose form, it is (in ratio with or without corn starch) one of the most widely used substances known as baby powder. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage, and the folia are not elastic, although slightly flexible. The Mohs scale of mineral hardness, based"
"less than 5% to over 20%. The existence of moganite was once regarded as dubious, but it is now officially recognised by the International Mineralogical Association. Chalcedony is more soluble than quartz under low-temperature conditions, despite the two minerals being chemically identical. This is thought to be because chalcedony is extremely finely grained (cryptocrystalline), and so has a very high surface area to volume ratio. It has also been suggested that the higher solubility is due to the moganite component. This table gives equilibrium concentrations of total dissolved silicon as calculated by ""PHREEQC"" (PH REdox EQuilibrium (in C language, USGS))"
"luster. The hardness is between 6.5 and 7 on the Mohs scale, and the specific gravity is between 4.0 and 4.7. It fractures in a conchoidal pattern and streaks grayish-green. It is also pyrognomic, which means that it becomes incandescent at a relatively low temperature. Gadolinite was named in 1800 for Johan Gadolin, the Finnish mineralogist-chemist who first isolated an oxide of the rare-earth element yttrium from the mineral in 1792. The rare earth gadolinium was also named for him. However, gadolinite does not contain more than trace amounts of gadolinium. When Gadolin analyzed this mineral, he missed an opportunity"
"Charlesite Charlesite is a sulfate mineral of the ettringite group. Charlesite was named in 1945 after Dr. Charles Palache mineralogist and professor at Harvard University for his work on minerals. This mineral is extremely rare, and when it is found it is often in crystal (but not gem) form. Its crystals are soft hexagonal, that can vary in color. Colors can range from clear to white, or even a pale yellow or pink. The brittle mineral's Mohs hardness is 2.5 with a specific gravity of 1.79. Though transparent to the eye the mineral has a white streak. Charlesite has only"