Diopside
Diopside is a very common mineral from the mineral class of " silicates and Germanates ". It crystallizes in the monoclinic crystal system with the composition CaMg [ Si2O6 ], and is therefore chemically seen a calcium magnesium silicate and structurally belongs to the chain silicates and thence to the pyroxene group.
Diopside developed short to long prismatic crystals, but is also found in the form of columnar, lamellar or granular mineral aggregates. In its pure form it is colorless and transparent. But it can also appear white and yellow, light to accept by foreign admixtures a dark green or black color by multiple refraction due to lattice defects or polycrystalline training, the transparency decreases correspondingly to the opacity.
Diopside, together with hedenbergite CaFe [ Si2O6 ] and augite (Ca, Na) (Mg, Fe, Al) [ (Si, Al) 2O6 ] a complete mixed batch.
Etymology and history
The name comes from the Greek diopside δίς dis for double ὄψις opsis for vision and ἰδού idos for shape and points out that the diopside crystals often occur as twins.
Was first described in 1800 by José mineral Bonifácio de Andrada e Silva, but under the name Coccolit. As localities he gave to the Hellesta and Åssebro iron mines in Swedish Södermanland. Later, however, could be demonstrated that d' Andradas mineral is identical to the diopside described by René -Just Haiiy 1806 and the name Coccolit was discredited.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz diopside belonged to the mineral class of " silicates and Germanates " and then to the Department of " chain silicates and phyllosilicates ( inosilicates ) ", where he, together with aegirine, augite, Esseneit hedenbergite, jadeite, Jervisit, Johannsenite, Kanoit, Klinoenstatit, Klinoferrosilit, Kosmochlor, Namansilit, Natalyit, omphacite, Petedunnit, pigeonite and spodumene the " pyroxene, clinopyroxene subgroup " with the system no. VIII/F.01 formed.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the diopside also in the class of " silicates and Germanates " and there in the department of " chains and chain silicates ( inosilicates ) " one. This division, however, is further subdivided according to the type of chain formation, so that the mineral according to its construction in the subsection " chain and chain silicates with 2- periodic single chains Si2O6; Pyroxene family " is to find where it together with augite, Esseneit, hedenbergite, Johannsenite and Petedunnit the ". Ca clinopyroxene, Diopsidgruppe "with the system no 9.DA.15 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the diopside in the class of " silicates and Germanates " and there in the department of " chain silicate minerals " one. Here he is with hedenbergite, augite, Johannsenite, Petedunnit, Esseneit and Davisit in the group of " C2 / c clinopyroxene (Ca - clinopyroxene ) " with the system no. 65.01.03a within the subdivision " chain silicates: Simple unbranched chains, W = 1 with chains P = 2" to find.
Modifications and variations
- Chromdiopsid - contain chromium, emerald green
- Baikalit - Ferrous, leek -green to olive green
- Diallag - aluminum and ferrous, green -brown to brown-black, pearly, rock-forming
- Fassait - iron-and aluminum-containing
- Fedorovit - sodium, aluminum and ferrous, light green from the Province of Rome
- Jeffersonit - manganese and zinc-containing
- Salit - greenish gray, rock-forming
Education and Locations
Diopside is a rock -forming mineral found in basic and ultrabasic rocks such as gabbro and peridotite. Accompanying minerals occur among others calcite, Chondrodite, forsterite, grossular, Clinohumite, monticellite, quartz, scapolite, tremolite, vesuvianite and wollastonite.
In Germany the mineral occurred among others in several places of the Black Forest, the Odenwald and the emperor chair in Baden- Württemberg; in the Fichtelgebirge, the Bavarian and Upper Palatinate Forest in Bavaria; at Giesel ( Neuhof ), high cities ( Bensheim ) and low -Ramstadt in Hesse; at Güntersen and Bad Harzburg in Lower Saxony; at Finkenberg and on Dächelsberg at Niederbachem in North Rhine -Westphalia; in many places in the Eifel region of Rhineland -Palatinate; in the Ore Mountains in Saxony; at Damsdorf in Schleswig -Holstein and in Ronneburg, Schnellbach ( flea Seligenthal ) and the Dolmar in Thuringia.
In Austria diopside has so far been found mainly in Carinthia, Lower Austria, Salzburg, Styria and Tyrol.
In Switzerland, the mineral occurs mainly in the cantons of Graubünden and Valais.
Even in rock samples from the Mid-Atlantic Ridge and the East Pacific Rise diopside could be detected.
Diopside in gemstone quality can be found in Brazil, Burma, Madagascar and Sri Lanka.
Outside the Earth could also already diopside are found, namely in rock samples from the moon, from Noctis Labyrinthus on Mars and the comet dust from Wild 2
Crystal structure
Diopside crystallized in the monoclinic space group C2 / c ( Raumgruppen-Nr. 15) with the lattice parameters a = 9.75 Å; b = 8.92 Å; c = 5.25 Å and 106.0 ° and β = 4 formula units per unit cell.
Use
Diopside gem quality are processed into semi-precious stones. This includes especially the Russian Chromdiopsid.