Talk:Augite

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Untitled[edit]

The Chemical formulas listed for Augite in the sidebar and the main text seem to contradict each other. Which is correct?

Hum, they both seem to be incorrect. The nomenclature of the pyroxenes is defined by Commission on New Minerals and Mineral Names of the International Mineralogical Association (final report)and Augite is a "quadrilateral" pyroxene, space group C2/c and "main composition" (Ca,Mg,Fe²⁺)₂SiO₃. It is still named augite if it has up to 20% of (NaFe³⁺) or (NaAl) component (more than this and it is aegirine-augite or omphacite, respectively) less then about 20% Ca leads to a change in space group (to P2₁/c) and then it's called pigeonite. 45-50% Ca and you are in the diopside - hedenbergite solid solution. This is not to say that you cannot have other elements in an augite crystal - but they are not a necessary component so should not be listed in the chemical formula (but noted elsewhere on the page). And don't take my percentages too literally, you have to do some interesting normalisations - and the normalisations are different for the Ca-Mg-Fe and the (NaAl)-(NaFe³⁺)-(Ca,Fe,Mg) plots. Andreww 20:52, 19 November 2006 (UTC)augite has a density of 5.5-6[reply]

Looks like there's a typo in the infobox code. Eddietoran (talk) 23:13, 1 December 2008 (UTC)[reply]

Fixed. Vsmith (talk) 03:35, 2 December 2008 (UTC)[reply]