{{Short description|Rare zeolite mineral}} {{Infobox mineral | name = Harmotome | boxwidth = | boxbgcolor = | image = Harmotome-227546.jpg | imagesize = 280px | alt = | caption = | category = Tectosilicate minerals | group = Zeolite group, phillipsite subgroup | formula = {{chem2|(Ba2(Si12Al4)O32*12H2O}}<ref name="mindat" /> | IMAsymbol = Hrm<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 = | strunz = | dana = | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''P2''<sub>1</sub>/m | unit cell = | color = | colour = | habit = | twinning = | cleavage = | fracture = | tenacity = | mohs = | luster = | streak = | diaphaneity = | gravity = 2.44 to 2.5 | density = | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}
'''Harmotome''' is a mineral, one of the rarer zeolites; a hydrated barium silicate with formula: {{chem2|(Ba2(Si12Al4)O32*12H2O}}.<ref name="mindat">{{cite web |title=Harmotome |url=https://www.mindat.org/min-1820.html |website=mindat.org |publisher=Hudson Institute of Mineralogy |access-date=23 February 2025}}</ref> It forms vitreous white well defined monoclinic crystals, often associated with calcite and other zeolites. It has a Mohs hardness of 4 to 5 and a specific gravity of 2.44 to 2.5.
==Name and discovery== Named from the Greek words {{langx|grc|ἁρμός|harmos}} (a joint) and {{langx|grc|τέμνειν|témnein}} (to cut) by René Just Haüy in 1801<ref name=EB1911>{{EB1911 |wstitle=Harmotome |volume=13 |page=10 |inline=1 |first=Leonard James |last=Spencer |authorlink=Leonard James Spencer}}</ref> because the pyramid divides parallel to the plane that passes through the terminal edges. It was first described in 1801 from an occurrence in the Harz Mountains, Lower Saxony, Germany.
==Location== Like other zeolites, harmotome occurs with calcite in the amygdaloidal cavities of volcanic rocks, for example, in the dolerites of Dumbartonshire, and as fine crystals in the agate-lined cavities in the melaphyre of Oberstein in Germany. It also occurs in gneiss, and sometimes in metalliferous veins. At Sankt Andreasberg in the Harz it is found{{by whom|date=March 2024}} in the lead and silver veins; and at Strontian in Argyll in lead veins, associated with brewsterite (a strontium and barium zeolite), barytes and calcite.<ref name=EB1911/>
==References== {{Reflist}} *[http://www.mindat.org/show.php?id=1820&ld=1&pho= Mindat w/ locations] *[http://webmineral.com/data/Harmotome.shtml Webmineral] *[http://dictionary.reference.com/browse/Harmotome?s=t Dictionary.com]
{{clear}} {{Right|228px}}
{{Commons}}
Category:Barium minerals Category:Calcium minerals Category:Sodium minerals Category:Potassium minerals Category:Aluminium minerals Category:Phillipsite subgroup Category:Monoclinic minerals Category:Minerals in space group 11
{{silicate-mineral-stub}}