Harmotome is a mineral, one of the rarer

zeolites Zeolites are a group of several Microporous material, microporous, crystalline aluminosilicate minerals commonly used as commercial adsorption, adsorbents and Catalysis, catalysts. They mainly consist of silicon, aluminium, oxygen, and have the ge ...

; a hydrated

barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

with formula: . It forms vitreous white well defined

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

crystals, often associated with

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

and other zeolites. It has a

Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

of 4 to 5 and a

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

of 2.44 to 2.5.

Name and discovery

Named from the Greek words (a joint) and (to cut) by

René Just Haüy René Just Haüy () FRS MWS FRSE (28 February 1743 – 1 June 1822) was a French priest and mineralogist, commonly styled the Abbé Haüy after he was made an honorary canon of Notre-Dame de Paris, Notre Dame. Due to his innovative work on cryst ...

in 1801 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 The Harz (), also called the Harz Mountains, is a Mittelgebirge, highland area in northern Germany. It has the highest elevations for that region, and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The nam ...

, Lower

Saxony Saxony, officially the Free State of Saxony, is a landlocked state of Germany, bordering the states of Brandenburg, Saxony-Anhalt, Thuringia, and Bavaria, as well as the countries of Poland and the Czech Republic. Its capital is Dresden, and ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

Location

Like other zeolites, harmotome occurs with calcite in the amygdaloidal cavities of volcanic rocks, for example, in the dolerites of

Dumbartonshire Dunbartonshire () or the County of Dumbarton is a historic county, lieutenancy area and registration county in the west central Lowlands of Scotland lying to the north of the River Clyde. Dunbartonshire borders Perthshire to the north, Stirling ...

, and as fine crystals in the agate-lined cavities in the melaphyre of

Oberstein Idar-Oberstein () is a town in the Birkenfeld district in Rhineland-Palatinate, Germany. As a ''Große kreisangehörige Stadt'' (large city belonging to a district), it assumes some of the responsibilities that for smaller municipalities in ...

in Germany. It also occurs in gneiss, and sometimes in metalliferous veins. At

Sankt Andreasberg Sankt Andreasberg () is a former independent city in the Goslar (district), district of Goslar, in Lower Saxony, Germany. Since 1 November 2011, it has formed part of the town Braunlage. It is situated in the Harz, approximately west of Braunlage ...

in the

Harz The Harz (), also called the Harz Mountains, is a highland area in northern Germany. It has the highest elevations for that region, and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The name ''Harz'' der ...

it is found in the lead and silver veins; and at

Strontian Strontian (; ) is the main village in Sunart, an area in western Lochaber, Scottish Highlands, Highland, Scotland, on the A861 road. Prior to 1975 it was part of Argyllshire. It lies on the north shore of Loch Sunart, close to the head of th ...

Argyll Argyll (; archaically Argyle; , ), sometimes called Argyllshire, is a Shires of Scotland, historic county and registration county of western Scotland. The county ceased to be used for local government purposes in 1975 and most of the area ...

in lead veins, associated with

brewsterite Brewsterite is the name of a series of tectosilicate minerals of the zeolite group. Prior to 1997, brewsterite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association changed it to a se ...

(a strontium and barium zeolite), barytes and calcite.

References

Mindat w/ locationsWebmineralDictionary.com
Barium minerals Calcium minerals Sodium minerals Potassium minerals Aluminium minerals Zeolites Monoclinic minerals Minerals in space group 11 {{silicate-mineral-stub