Diopside
Diopside is a calcium-magnesium-silicate and one of the most common minerals of the pyroxene-group. It forms complete isomorphous series with hedenbergite and johannsenite.
Three views of a diopside from the Ziller Valley, Tyrol, Austria
Origin of name: from Greek δίς dis meaning double, ὄψις opsis meaning sight or vision and ἰδού idos meaning shape. One interpretation says, this hints to the fact that diopsides often appear as twinned crystals. According to another view, it alludes to the two possible orientations of the prism faces of diopside crystals.
Synonyms and trade names: in gemmological literature and data banks one finds a number of synonyms: acantoide, acimite-diopside, alalite, chrome-augite, coccolite, dekalbite, diopsidic pyroxene, malacolite, mussite, protheite, sahlite, tashmarine and traversellite. However, in more than fourty years we did not encounter a single one of these names, neither in gemmology, nor in the gem trade. Thus we assume that one can safely call this list of synonyms historical.
Can be confused with: a number of other green gem stones like tourmaline, tsavorite and demantoide garnet, green sapphire, green zircon, green spinel, grren zircon, epidote, vesuvianite (idocrase) and sphene (titanite)
Localities: diopside is petrogenetic (rock-forming) and as such very common indeed. At the time of writing (2025) mindat lists more than 3000 deposits worldwide, including Antarctica.
Handling: regarding diopside´s susceptibility to heat, acids and brines we have contradictory reports. Goldsmiths told us that all contact with boric acid and galvanic baths must be avoided and that diopside should not be cleaned ultrasonically.
However, German Wikipedia as well as Mineralienatlas entries state, that it is virtually unsusceptible to all acids except hydrofluoric acid.
Diopside shows distinct cleavage. Apply pressure carefully during setting.
Worth knowing: despite the abundance of diopside, facettable material is rare. Occasionally the very attractive chrome diopside is used in jewellery, as is star diopside and the much rarer diopside cat´s eye. However, because of rather low hardness and good cleavage, all diopsides should be worn with care.
Chromdiopside, star diopside and diopside cat´s eye
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