Boracite

Boracite

Boracite is a magnesium borate chloride mineral with formula: Mg3B7O13Cl. It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic - pyramidal crystal system. Boracite also shows pseudo-isometric cubical and octahedral forms. These are thought to be the result of transition from an unstable high temperature isometric form on cooling. Penetration twins are not unusual. It occurs as well formed crystals and dispersed grains often embedded within gypsum and anhydrite crystals. It has a Mohs hardness of 7 to 7.5 and a specific gravity of 2.9. Refractive index values are nα = 1.658 - 1.662, nβ = 1.662 - 1.667 and nγ = 1.668 - 1.673. It has a conchoidal fracture and does not show cleavage. It is soluble in water.

Boracite is typically found in evaporite sequences associated with gypsum, anhydrite, halite, sylvite, carnallite, kainite and hilgardite. It was first described in 1789 for specimens from its type locality of Kalkberg hill, Lüneburg, Lower Saxony, Germany. The name is obviously derived from its boron content (19 to 20% boron).

References

*Palache, C., H. Berman, and C. Frondel (1951) "Dana’s system of mineralogy", 7th edition, v. II, pp.378–381.
* [http://webmineral.com/data/Boracite.shtml Webmineral data]
* [http://www.mindat.org/min-721.html Mindat with location data]
* [http://rruff.geo.arizona.edu/doclib/hom/boracite.pdf Mineral Data Publishing]


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • boracite — ● boracite nom féminin (de borax) Chloroborate naturel de magnésium. boracite [bɔʀasit] n. f. ÉTYM. XIXe; in Littré; de borax. ❖ ♦ Minér …   Encyclopédie Universelle

  • Boracite — Bo ra*cite, n. (Min.) A mineral of a white or gray color occurring massive and in isometric crystals; in composition it is a magnesium borate with magnesium chloride. [1913 Webster] …   The Collaborative International Dictionary of English

  • boracite — s. f. [Mineralogia] Borato de magnésia natural.   ♦ Grafia no Brasil: boracita …   Dicionário da Língua Portuguesa

  • boracite — [bôr′ə sīt΄] n. [< BORAX + ITE1] a very hard, brittle, orthorhombic mineral, magnesium borate, Mg3B7O13Cl, formed by the evaporation of salt water: it has a strong pyroelectric property …   English World dictionary

  • boracite — boracitas statusas T sritis chemija apibrėžtis Mineralas. formulė (Mg,Fe,Mn)₃[Cl|B₇O₁₃] atitikmenys: angl. boracite rus. борацит …   Chemijos terminų aiškinamasis žodynas

  • boracite — /bawr euh suyt , bohr /, n. a strongly pyroelectric mineral, a borate and chloride of magnesium, Mg6Cl2B14O26, occurring in white or colorless cubic crystals or fine grained masses. [1800 10; borac (s. of BORAX1) + ITE1] * * * ▪ mineral… …   Universalium

  • boracite — noun A mixed chloride and borate of magnesium that occurs as a white to green crystalline evaporite, with the chemical formula MgBOCl …   Wiktionary

  • boracite — (bo ra si t ) s. f. Substance vitreuse qu on trouve dans les carrières de plâtre (sous borate de magnésie). ÉTYMOLOGIE    Borax …   Dictionnaire de la Langue Française d'Émile Littré

  • boracite — pl.f. boraciti …   Dizionario dei sinonimi e contrari

  • boracite — bo·ra·cite …   English syllables

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”