Clinohumite
A mixed cushion-cut clinohumite gemstone, 21.34 carats (4.268 g), 17.8 x 16 mm.
General
Category	Mineral
Formula	(Mg,Fe)7(SiO4)3(F,OH)2
Identification
Color	Brownish to orange, yellow, red
Habit	Granular, prismatic, twinned
System	Monoclinic
Cleavage	Poor, basal
Fracture	Conchoidal to uneven
Hardness	6
Luster	Vitreous to resinous
RI	1.631–1.668 (DR +0.028)
Pleochroism	Yellow to colorless
Streak	White
SG	3.2-3.9
Fusibility	No data
Solubility	No data
Major varieties
Titanclinohumite	Titanoan; (Mg,Fe2+,Ti)9[(F,OH,O)2|(SiO4)4]

Clinohumite is an uncommon member of the humite group of minerals, a magnesium silicate according to the chemical formula (Mg,Fe)₇(SiO₄)₃(F,OH)₂. Most commonly found as tiny indistinct grains, large euhedral clinohumite crystals are sought by collectors and occasionally fashioned into bright, yellow-orange gemstones. Only two sources of gem-quality material are known: the Pamir Mountains of Tajikistan, and the Taymyr region of northern Siberia. It is one of two humite group minerals that have been cut into gems, the other being the much more common chondrodite. Image File history File linksMetadata Download high resolution version (830x776, 98 KB)Mined Clinohumite IN GEMSTONE FORM From Pamir MTS - OLD USSR Natural Gold-Orange 7 Color Cushion Cut 17. ... Image File history File linksMetadata Download high resolution version (830x776, 98 KB)Mined Clinohumite IN GEMSTONE FORM From Pamir MTS - OLD USSR Natural Gold-Orange 7 Color Cushion Cut 17. ... The carat is a unit of mass used for gems, and equals 200 milligrams. ... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For fractures in bones, see Fracture (bone). ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed relative to vacuum. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... Pleochroism is an optical phenomenon where due to double refraction of light by a colored gem or crystal, the light is divided into two paths which are polarized at a 90° angle to each other. ... The term streak is used in several ways: Streaking, the act of running around nude in public places. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Fusibility is the ease with which a material will melt. ... A substance is soluble in a fluid if it dissolves in that fluid. ... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... In chemistry, a silicate is a compound consisting of silicon and oxygen (SixOy), one or more metals, and possibly hydrogen. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Quartz 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. ... A selection of gemstone pebbles made by tumbling rough rock with abrasive grit, in a rotating drum. ... Located in Central Asia, the Pamir Mountains are formed by the junction of the Tian Shan, Karakoram, Kunlun, and Hindu Kush ranges. ... Taymyr Peninsula is a peninsula in Siberia that forms the most northern part of mainland Asia. ... Siberia Siberia (Russian: , common English transliterations: Sibir’, Sibir; from the Tatar for “sleeping land”) is a vast region of Russia and northern Kazakhstan constituting almost all of northern Asia. ... Humite is a mineral of a transparent vitreous brown color, found in the ejected masses of Vesuvius. ... Chondrodite is a nesosilicate mineral with formula (Mg,Fe)5(F,OH)2(SiO4)2. ...

Properties

A monoclinic mineral, clinohumite is typically a dark to light brownish or orangy yellow, somewhat resembling the hessonite variety of grossular. Clinohumite's crystal habit is usually granular, but may also be prismatic; crystals are almost always small. Simple and multiple crystal twinning (on {001}) is common, resulting in a highly variable habit. Clinohumite is brittle with a hardness of 6 and a poor basal cleavage. Its specific gravity is 3.2–3.4, and its fracture is conchoidal to uneven; its streak is white. In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... Cinnamon Stone is a variety of garnet, belonging to the lime-alumina type, known also as essonite or hessonite, from the Greek hÄ“ssōn, inferior, in allusion to its being less hard and less dense than most other garnet. ... The garnet group of minerals show crystals with a habit of rhombic dodecahedrons and trapezohedrons. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... In geometry, a prism is a polyhedron made of two parallel copies of some polygonal base joined by faces that are rectangles or parallelograms. ... A twin boundary occurs when two crystals of the same type intergrow, so that only a slight misorientation exists between them. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... For fractures in bones, see Fracture (bone). ... A conchoidal fracture is produced when some types of fine-grained mineral, such as obsidian and flint, are broken. ... The term streak is used in several ways: Streaking, the act of running around nude in public places. ...

Clinohumite's transparency ranges from transparent to translucent; its luster ranges from a dull vitreous to resinous. Its refractive index (as measured via sodium light, 589.3 nm) is as follows: α 1.631; β 1.638–1.647; γ 1.668;, with a maximum birefringence of 0.028 (biaxial positive). Under shortwave ultraviolet light, some clinohumite may fluoresce an orangy yellow; there is little to no response under longwave UV. For the file system called Lustre, see Lustre (file system) Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed relative to vacuum. ... A sodium vapor lamp is a gas discharge lamp which uses sodium in an excited state to produce light. ... A nanometre (American spelling: nanometer) is 1. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of the visible region, but longer than that of soft X-rays. ... Fluorescence induced by exposure to ultraviolet light in vials containing various sized cadmium selenide (CdSe) quantum dots. ...

The Taymyr material is reported to be a dark reddish brown while the Pamir material is a bright yellow to orange or brownish orange. The Pamir material also has a hardness slightly greater than 6, a lower specific gravity (3.18), and higher maximum birefringence (0.036). Phillip Youngman, master faceter of Los Osos, California, noticed not only that Pamir material is harder than expected, but also that it is less brittle than expected. Youngman observed that clinohumite reacted like beryl to cutting and polishing, and that it reminded him of polishing diopside. Facets are flat faces on geometric shapes. ... Baywood-Los Osos is a census-designated place located in San Luis Obispo County, California. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 3rd 410,000 km² 402. ... This article is about the mineral, for the rifle see Beryl assault rifle. ... Diopside is a monoclinic pyroxene mineral with composition MgCaSi2O6. ...

Like other members of the humite group, the relative amounts of hydroxyl and fluorine vary in clinohumite, and iron commonly substitutes for some of the magnesium, bringing about changes in physical and optical properties. Titanium substitution also causes pronounced changes in optical properties, producing the variety titanclinohumite. Consequently, it is relatively easy to determine that a stone is a humite group mineral, but difficult to determine exactly which member. Other common impurities of clinohumite include aluminium, manganese, and calcium. Hydroxyl group The term hydroxyl group is used to describe the functional group -OH when it is a substituent in an organic compound. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance pale greenish-yellow gas Atomic mass 18. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number manganese, Mn, 25 Chemical series transition metals Group, Period, Block 7, 4, d Appearance silvery metallic Atomic mass 54. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ...

Formation and occurrence

Clinohumite is the product of contact metamorphism and is commonly found as indistinct grains embedded in limestone. Its type occurrence is within the limestone ejecta of the Mount Vesuvius volcano complex near Naples, Italy, where clinohumite was discovered in 1876. The aforementioned gem-quality occurrences of Pamir and Taymyr were discovered only recently: the former in the early 1980s, and the latter in 2000. These deposits are scarce and only sporadically mined, so clinohumite remains one of the rarest gemstones with only a few thousand carats known to exist in private collections. Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ... Limey shale overlaid by limestone. ... This article is about the volcano in Italy. ... View of Mount Rainier, a stratovolcano. ... Alternate uses: See Naples (disambiguation) Naples (Italian Napoli, Neapolitan Napule, from Greek Νέα-Πόλις, latinised in Neapolis) is the largest town in southern Italy, capital of Campania region. ... 1876 is a leap year starting on Saturday. ... The 1980s decade refers to the years from 1980 to 1989, inclusive. ... This article is about the year 2000. ...

Other (non-gemmy) occurrences of clinohumite include: the Sør Rondane and Balchen Mountains of Antarctica; Mount Bischoff, Waratah, Tasmania; the Saualpe Mountains of Carinthia, the Koralpe Mountains of Styria, and the Vals, Virgen, and Ziller valleys of the Tyrol, Austria; the Jacupiranga mine of Cajati, São Paulo State, Southeast Region, Brazil; the Pirin Mountains of Bulgaria; Bancroft, Ontario, Notre Dame du Laus, Wakefield, and Villedieu Township, Quebec, Canada; Southern and Western Finland; Bavaria and Saxony, Germany; eastern Greenland; Tamil Nadu, India; Honshu Island, Japan; Suan, North Korea; Nordland, Norway; KwaZulu-Natal and Northern Cape Province, South Africa; Andalusia, Spain; Värmland and Västmanland, Sweden; Isle of Skye, Scotland; and the states of California, Colorado, Massachusetts, New Jersey, New Mexico, New York, Oklahoma, Utah, and Washington, USA. Carinthia (German Kärnten, Slovenian KoroÅ¡ka) is a Austrian state or Land, located in the south of Austria. ... Styria (die Steiermark in German, Å tajerska in Slovenian) is a state or Land, located in the south east of Austria. ... The Tyrol is a historical region in Western Central Europe, which includes the Austrian state of Tyrol (consisting of North Tyrol and East Tyrol) and the Italian regions known as the South Tyrol and Trentino. ... Cajati is a municipality in the state of São Paulo in Brazil. ... São Paulo is a state in Brazil. ... The Southeast Region of Brazil is composed by the states of Espírito Santo, Minas Gerais, Rio de Janeiro and São Paulo. ... Vihren from the south The Pirin Mountains (Bulgarian: Пирин) are a mountain range in southwest Bulgaria, with Vihren (2,914 m high) the highest peak, situated at , . The range extends about 40 km northwest-southeast, and about 25 km wide. ... Bancroft is a town on the York River in Hastings County in the Canadian province of Ontario. ... Wakefield is a village on the Gatineau River, in the Outaouais region of Quebec. ... Motto: Je me souviens (French: I remember) Official languages French Capital Quebec City Largest city Montreal Lieutenant-Governor Lise Thibault Premier Jean Charest (PLQ) Parliamentary representation  - House seat  - Senate seats 75 24 Area  - Total  - % water Ranked 2nd 1,542,056 km² 11. ... The Province of Southern Finland is a province of Finland. ... The Province of Western Finland is a province of Finland. ... The Free State of Bavaria  (German: Freistaat Bayern), with an area of 70,553 km² (27,241 square miles) and 12. ... The Free State of Saxony (German: Freistaat Sachsen; Sorbian: Swobodny Stata Sakska) is at a land area of 18,413 km² and a population of 4. ... Tamil Nadu (தமிழ் நாடு, Land of the Tamils) is a state at the southern tip of India. ... HonshÅ«   listen? (本州) is the largest island of Japan, called the Mainland; it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait. ... Nordland is a county in Norway, bordering Troms and Nord-Trøndelag. ... Capital Pietermaritzburg Largest city Durban Area  - Total Ranked 7th 92,100 km² Premier (List) Sbu Ndebele (ANC) Population   - 2001   - 1996   - Density Ranked 1st 9,426,019 8,417,021 102/km² (2001) Languages isiZulu (80. ... Northern Cape is a province of South Africa, created in 1994 when the Cape Province was split up. ... Motto: Dominator Hercules Fundator Andalucía por sí, para España y la humanidad (Andalusia for herself, for Spain, and for humanity) Capital Seville Area  â€“ Total  â€“ % of Spain Ranked 2nd  87 268 km²  17,2% Population  â€“ Total (2003)  â€“ % of Spain  â€“ Density Ranked 1st  7 478 432  17,9%  85,70... â–¶(?) is a historical province or landskap in the west of middle Sweden. ...  Västmanland? is a historical Province or landskap in middle Sweden. ... The Old Man of Storr, Skye The Isle of Skye, usually known simply as Skye (An t-Eilean Sgitheanach in Scottish Gaelic) is the largest and most northerly island in the Inner Hebrides of Scotland. ... Royal motto: Nemo me impune lacessit (English: No one provokes me with impunity) Scotlands location within the UK Languages English, Gaelic, Scots Capital Edinburgh Largest city Glasgow First Minister Jack McConnell Area - Total - % water Ranked 2nd UK 78,782 km² 1. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 3rd 410,000 km² 402. ... Official language(s) English Capital Denver Largest city Denver Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 8th 269,837 km² 451 km 612 km 0. ... Official language(s) English Capital Boston Largest city Boston Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 44th 27,360 km² 305 km 80 km 25. ... Official language(s) None defined, English de facto Capital Trenton Largest city Newark Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 47th 22,608 km² 110 km 240 km 14. ... Official language(s) English and Spanish Capital Santa Fe Largest city Albuquerque Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 5th 315,194 km² 550 km 595 km 0. ... Official language(s) English Capital Albany Largest city New York City Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 27th 141,205 km² 455 km 530 km 13. ... Official language(s) None Capital Oklahoma City Largest city Oklahoma City Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 20th 181,196 km² 355 km 645 km 1. ... Official language(s) English Capital Salt Lake City Largest city Salt Lake City Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 13th 219,887 km² 435 km 565 km 3. ... Official language(s) None Capital Olympia Largest city Seattle Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 18th 184,824 km² 385 km 580 km 6. ...

References

• Arem, Joel E. (1977). Color encyclopedia of gemstones. Van Nostrand Reinhold Company, New York, 149 pages
• Deer, W.A., R.A. Howie, and J. Zussman. (1966). An introduction to the rock forming minerals. Longsman, Green and Co., Ltd., London, 528 pages.
• Henn, U., Hyršl, J., and Milisenda, C. (2000). Gem-quality clinohumite from Tajikistan and the Taymyr region, Northern Siberia. Journal of Gemmology, Vol. 27, No. 6, pp. 335–340.
• Mindat.org. Clinohumite. Retrieved May 9, 2005 from http://www.mindat.org/min-1077.html
• Roberts, W.L., G.R. Rapps, Jr., and J. Weber. (1975). Encyclopedia of minerals. Van Nostrand Reinhyold Company, New York, 693 pages.
• Webster, R., Read, P. G. (Ed.) (2000). Gems: Their sources, descriptions and identification (5th ed.), p. 327. Butterworth-Heinemann, Great Britain. ISBN 0750616741
• Zotter, David (2006). Reference of pictures from Clinohumite collection, http://www.clinohumite.com/