Editing Tourmaline (section)

{{Short description|Cyclosilicate mineral group}}
{{Other uses}}
{{Infobox mineral
| boxbgcolor=#a7a927
| boxwidth    = 100 px
| name        = Tourmaline 
| category    = [[Cyclosilicate]]
| image       = Tourmaline-121240.jpg
| imagesize   = 260px
| alt         = A stone cut open and polished, revealing a bright rainbow of colors
| caption     = 
| formula     = {{chem2|(Ca,K,Na, [[vacancy defect|▢]])(Al,Fe,Li,Mg,Mn)3(Al,Cr,Fe,V)6<br>(BO3)3(Si,Al,B)6O18(OH,F)4}}<ref name="GRG">{{cite book |publisher=[[Gemological Institute of America]] |title=GIA Gem Reference Guide |year=1995 |isbn=0-87311-019-6}}</ref><ref name="mindat">{{cite web |url=https://mindat.org/min-4003.html |title=Tourmaline |publisher=[[Mindat.org]] |access-date=2005-09-12 |archive-url=https://web.archive.org/web/20051228163105/http://www.mindat.org/min-4003.html |archive-date=2005-12-28 |postscript=. This website details specifically and clearly how the complicated chemical formula is structured.}}</ref>
| IMAsymbol   = Tur<ref>{{cite journal |last=Warr|first=L. N. |year=2021 |title=IMA–CNMNC approved mineral symbols |journal=[[Mineralogical Magazine]] |volume=85 |issue=3 |pages=291–320 |doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}</ref>
| molweight   = 
| system      = [[hexagonal crystal family|Trigonal]]
| class       = Ditrigonal pyramidal (3m)<br>[[H-M symbol]]: (3m)
| symmetry    = ''R3m'' (no. 160)
| color       = Most commonly black, but can range from colorless to brown, red, orange, yellow, green, blue, violet, pink, or hues in-between. It can also be bi-colored, or even tri-colored. Rarely, it can be found as neon green or electric blue.
| habit       = Parallel and elongated; [[acicular (crystal habit)|acicular]] [[prism (geology)|prisms]], sometimes radiating; massive; scattered grains (in granite)
| twinning    = 
| cleavage    = Indistinct
| fracture    = Uneven, small [[conchoidal fracture|conchoidal]]
| tenacity    = Brittle
| mohs        = 7.0–7.5
| luster      = Vitreous, sometimes resinous
| polish      = Vitreous<ref name="GRG" />
| refractive  = ''n''{{sub|ω}} = 1.635–1.675<br>''n''{{sub|ε}} = 1.610–1.650
| opticalprop = [[birefringence|Double-refractive]], uniaxial negative<ref name="GRG" />
| birefringence = −0.018 to −0.040; typically about −0.020 but in dark stones it may reach −0.040<ref name="GRG" />
| dispersion  = 0.017<ref name="GRG" />
| pleochroism = {{plainlist|
* Typically moderate to strong<ref name="GRG" />
* Red: definite; dark red, light red
* Green: strong; dark green, yellow-green
* Brown: definite; dark brown, light brown
* Blue: strong; dark blue, light blue}}
| fluorescence= Pink stones; inert to very weak red to violet in long and short wave<ref name="GRG" />
| absorption  = Strong narrow band at 498&nbsp;nm, and almost complete absorption of red down to 640&nbsp;nm in blue and green stones; red and pink stones show lines at 458 and 451&nbsp;nm, as well as a broad band in the green spectrum<ref name="GRG" />
| streak      = White
| gravity     = 3.06+0.20–0.06<ref name="GRG" />
| density     = 2.82–3.32
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = [[transparency and translucency|Translucent]] to [[opacity (optics)|opaque]] 
| other       = 
}}
[[File:Tourmaline gisements.jpg|thumb|upright=1.3|Main tourmaline producing countries]]

'''Tourmaline''' ({{IPAc-en|ˈ|t|ʊər|m|ə|l|ɪ|n|,_|-|ˌ|l|iː|n|audio=LL-Q1860 (eng)-NaomiAmethyst-tourmaline.wav}} {{respell|TOOR|mə|lin|,_|-|leen}}) is a [[crystalline]] [[silicate mineral|silicate]] [[mineral group]] in which [[boron]] is [[chemical compound|compounded]] with [[chemical element|elements]] such as [[aluminium]], [[iron]], [[magnesium]], [[sodium]], [[lithium]], or [[potassium]]. This [[gemstone]] comes in a wide variety of colors.

The name is derived from the [[Sinhala language|Sinhalese]] {{Transliteration|si|tōramalli}} ({{wikt-lang|si|ටෝරමල්ලි}}), which refers to the [[carnelian]] gemstones.<ref>{{Cite web|title=tourmaline|url=https://www.lexico.com/definition/tourmaline|archive-url=https://web.archive.org/web/20211016064413/https://www.lexico.com/definition/tourmaline|archive-date=October 16, 2021|url-status=live|access-date=2021-03-19|website=[[Oxford Dictionaries (website)|Oxford Dictionaries]]|language=en}}</ref>