# Hydrogrossular

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Hydrogrossular
> Markdown URL: https://mediated.wiki/source/Hydrogrossular.md
> Source: https://en.wikipedia.org/wiki/Hydrogrossular
> Source revision: 1269934151
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Calcium aluminium garnet}}
{{Infobox mineral
| name        = Hydrogrossular
| category    = [Nesosilicate](/source/Silicate_minerals)
| boxwidth    = 
| boxbgcolor  = 
| image       = File:Hydrogrossulaar.jpg
| imagesize   = 
| caption     = 
| formula     = Ca<sub>3</sub>Al<sub>2</sub>(SiO<sub>4</sub>)<sub>3−x</sub>(OH)<sub>4x</sub> 
| IMAsymbol   = Hgrs<ref>{{Cite journal|last=Warr|first=L.N.|date=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      = [Cubic](/source/cubic_crystal_system)
| color       = green to bluish green, pink, white, gray 
| habit       = [Massive](/source/Crystal_habit)
| twinning    = 
| cleavage    = none
| fracture    = conchoidal 
| mohs        = 7–7.5 
| luster      = vitreous
| polish      = vitreous to subadamantine 
| refractive  = {{val|1.810|0.004|0.020}}
| opticalprop = single refractive, anomalous aggregate reaction 
| birefringence = none
| dispersion  = 
| pleochroism = none
| fluorescence= inert 
| absorption  = dark green hydrogrossular often shows cutoff below 460 nm. Other color stones may show line around 463 nm, indicating some [idocrase](/source/idocrase) content
| streak      = 
| gravity     = {{val|4.15|0.05|0.03}}
| density     = 
| melt        = 
| fusibility  = 
| diagnostic  = 
| solubility  = 
| diaphaneity = 
| other       = 
| references  = Gemological Institute of America<ref name="GRG">[Gemological Institute of America](/source/Gemological_Institute_of_America), ''GIA Gem Reference Guide'' 1995, {{ISBN|0-87311-019-6}}</ref>
}}
'''Hydrogrossular''' is a [calcium](/source/calcium) [aluminium](/source/aluminium) [garnet](/source/garnet) series (formula: Ca<sub>3</sub>Al<sub>2</sub>(SiO<sub>4</sub>)<sub>3−''x''</sub>(OH)<sub>4''x''</sub>, with hydroxide (OH) partially replacing silica (SiO<sub>4</sub>)). The endmembers of the hydrogarnet family ([grossular](/source/grossular), [hibschite](/source/hibschite), and [katoite](/source/katoite)) depend on the degree of substitution (''x''):<ref name="GRG"/>

* grossular: ''x'' = 0
* hibschite: 0.2 < ''x'' < 1.5
* katoite: 1.5 < ''x'' < 3.

Hydrogrossular is a garnet variety in which a Si<sup>4+</sup> is missing from a tetrahedral site. Charge balance is maintained by bonding a H<sup>+</sup> to each of the four oxygens surrounding the vacant site.

Hydrogrossular is found in [massive crystal habit](/source/Crystal_habit), sometimes grown in with [idocrase](/source/idocrase).<ref name="GRG"/>

Hydrogrossular is [translucent](/source/translucent) to [opaque](/source/Opacity_(optics)), and found in green to bluish green, pink, white, and gray. The cause of the green color is [chromium](/source/chromium), and possibly [iron](/source/iron). Pink hydrogrossular is caused by the presence of [manganese](/source/manganese). Hydrogrossular may have dark gray to black small inclusions.<ref name="GRG"/> It has similarities to [jade](/source/jade), and has the [misnomer](/source/misnomer)s ''Transvaal jade'', and ''African jade''.<ref name="GRG"/>

Hydrogrossular is sometimes used as a [gemstone](/source/gemstone), being [cabochon](/source/cabochon) cut, or made into [bead](/source/bead)s. Sources for green and pink hydrogrossular are [South Africa](/source/South_Africa), [Canada](/source/Canada), and the [United States](/source/United_States). White hydrogrossular is sourced from [Burma](/source/Burma) and [China](/source/China).<ref name="GRG"/>

==References==
{{reflist}}

== External links ==
* [http://www.mindat.org/min-8635.html Grossular-Hibschite Series on Mindat]

Category:Aluminium minerals
Category:Calcium minerals
Category:Cement
Category:Garnet gemstones

{{silicate-mineral-stub}}

---
Adapted from the Wikipedia article [Hydrogrossular](https://en.wikipedia.org/wiki/Hydrogrossular) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Hydrogrossular?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.