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Space/Science » in reply to Smooth inclusions in Wishstone rock.

re: Smooth inclusions in Wishstone rock.
Nick Hoffman — (archived)

The inclusions are a very familiar shape - we've actually seen something like these in other Mars rocks, too.

They appear to be twinned crystals or crystal fans with stumpy hexagonal prismatic cross-section.

Possible candidates are Hornblende (complex silicate common in basic igneous rocks), Tourmaline (Ditto), Nepheline (Na,K)AlSiO4, Corundum (Al2O3).

Of these, Nepheline would be mildly interesting, since it implies calc-alkaline volcanism (though it is becoming more likely that Mars is more prone to this than Earth is), and Corundum which is really a metamorphic mineral.

Less likely possibilities: Muscovite (Mica), Pyrrhotite (FeS), Chalcocite (Cu2S), Stromeyerite (AgCuS), Wurtzite (ZnS), Willemite (Zn2SiO4), Aragonite (CaCO3) Witherite (BaCO3), Vanadinite or other Apatite minerals (Pb5(VO4,PO4,AsO4)3Cl, Beryl (gemstone)...

(Quartz also has this morphology but it would be odd to find a quartz-normative rock with excellent crystal development amongst all these basic igneous rocks - but hey, they do say it's different)

Obviously, some of the latter, odder minerals would be exciting, but are unlikely. The likely ones are not particularly unusual.

jms? Any comments?

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