MSH is the type, and so far, only known locality for garronite-Na. This is a “typical” sample, but it has not been analyzed. (EDS wouldn’t be sufficient, and XRD and WDS are expensive – WDS extremely so.) The specimen is ex Gilles Haineualt, who found the holotype material for garronite-Na. According to László Horváth (private communication), the holotype material was found in 1991 in the form of botryoidal masses in igneous breccia. The matrix for this specimen is glassy albite sprinkled with tiny epididymite crystals. Proabably it is from a pegmatite, rather than breccia. However all garronite at MSH – whether from breccia or pegmatites - is apparently garronite-Na, so it doesn’t really matter.
The two pairs of close-up photos (FOV 2.8 x 2.4 mm and 2.1 x 3.0 mm resp) are slightly different views of the two garronite crystals on the specimen. They have diameters ca 0.9 mm. The little “teeth”, which are sprinkled all over the albite are probably epididymite or eudidymite. (They are so tiny that it’s hard to be sure of the exact species, but I think they are epididymite.)
Almost all “garronite” from other localities is massive. The most notable exception is Fara Vicenino in Italy, where, according to Tschernich, pseudo-octahedral di-pyramids of garronite-Ca, often inter-grown with gismondine and gobbinsite, occur. The “crystals” on this specimen appear to be crudely (pseudo) octahedral or cubo-octahedral, but under high magnification, they seem to be a bit “bumpy” or “grainy”. Somewhat similar, but pure white, “crystals” from a completely different find turned out to be gobbinsite. Those are probably pseudomorphs – perhaps after garronite – because some have hollow centers.
So is this garronite-Na or not? Given that the specimen (ultimately) came from Gilles, I think that it is. But there could well be other phases such gobbinsite and phillipsite present. (According to Tschernich, phillipsite often forms a thin crust on garronite.)
Single item shipping weight is 2.7 oz. For destinations outside the USA, up to a total weight of 8 oz (225 g), this could be combined with other items from this or future auctions for the same postage.
Within the USA weight isn’t much of an issue - each additional ounce requires about $0.20 in additional postage. Above a total weight of 13 oz, I will use “own box” Priority Mail for $9.25.
