Editing Peridot (section)

{{short description|Green gem-quality mineral}}
{{other uses}}
{{Infobox mineral
| name   =   Peridot
| category    = [[Silicate mineral]]s
| boxwidth    = 
| boxbgcolor  = #acdf7d
| image       = Forsterite-Olivine-tmu14a.jpg
| image size  = 
| caption     = 
| formula     = {{chem2|(Mg,Fe)2SiO4}}
| molweight   = 
| color       = Yellow, to [[chartreuse (color)|yellow-green]], [[olive (color)|olive-green]], to brownish, sometimes a [[lime (color)|lime green]], to emerald hue
| habit       = 
| system      = [[orthorhombic crystal system|Orthorhombic]]
| twinning    = Uncommon, simple twinning can occur on {100}, {011},{012}, cyclic twinning on {031} 
| cleavage    = Poor on {010} and {110}, {010} cleavage improves with increasing iron content
| fracture    = [[conchoidal fracture|Conchoidal]]
| mohs        = 6.5–7
| luster      = Vitreous to oily
| refractive  = 1.64–1.70 
| opticalprop = 
| birefringence = +0.036
| pleochroism = Weak pale yellow-green to yellow, yellow to yellow orange
| streak      = Colorless
| gravity     = 3.2–4.3
| melt        = between 1,200 and 1,900°[[celsius|C]]
| fusibility  = Infusible avoid thermal shock 
| diagnostic  = 
| solubility  = Slowly forms gelatinous silica in {{chem2|H Cl}}
| diaphaneity = Translucent to transparent 
| other       = 
}}

'''Peridot''' ({{IPAc-en|ˈ|p|ɛ|r|ɪ|ˌ|d|ɒ|t|,_|-|ˌ|d|oʊ}} {{respell|PERR|ih|dot|,_|-|⁠doh}}), sometimes called '''chrysolite''', is a [[lime (color)|yellow-green]] transparent variety of [[olivine]]. Peridot is one of the few [[gemstone]]s that occur in only one color.

Peridot can be found in [[mafic]] and [[ultramafic rock]]s occurring in [[lava]] and [[peridotite]] [[xenolith]]s of the [[mantle (geology)|mantle]]. The gem occurs in silica-deficient rocks such as volcanic [[basalt]] and [[pallasite|pallasitic]] [[meteorite]]s. Along with [[diamonds]], peridot is one of only two gems observed to be formed not in [[Earth's crust]], but in the molten rock of the upper mantle.<ref name="Rock & Gem Magazine 2023">{{cite magazine |title=Peridot crystals: Formation & locations |magazine=Rock & Gem Magazine |date=2023-07-10 |quote=Get to know this August birthstone |url=https://www.rockngem.com/peridot-crystals/ |via=rockngem.com |access-date=2024-01-21 |df=dmy-all }}</ref> Gem-quality peridot is rare on Earth's surface due to its susceptibility to alteration during its movement from deep within the mantle and weathering at the surface.<ref name="The University of Texas at Austin Gems">{{cite web | title=Peridot |department=Gem notes |id=course&nbsp;347k |website=geo.utexas.edu |publisher=[[UT-Austin|The University of Texas]] |place=Austin, TX |series=Geology Department |url=https://www.geo.utexas.edu/courses/347k/redesign/Gem_Notes/Peridot/peridot_main.htm |access-date=2024-01-21 }}</ref> Peridot has a [[chemical formula]] of {{nobr| {{chem2|(Mg,Fe)2SiO4}}}}.

Peridot is one of the [[birthstone]]s for the month of August.<ref>{{cite periodical |title=Color, meanings, and symbolism [of] August birthstone peridot |periodical=[[Old Farmer's Almanac]] |via=almanac.com |url=https://almanac.com/august-birthstone-color-and-meaning }}</ref>