The matrix is largely microcline in the form of thick tabular crystals. There is also ancylite – probably calcioancylite-(Ce) – in the form of nondescript grains replacing other minerals and filling small cavities. In addition there are small, well-formed, prisms of an unidentified amphibole partly encrusted by an even more unidentified Ca-Y mineral. These last two are for those who like puzzles – I have provided EDS scans. See the photo descriptions for my guess for the amphibole.
The main crystals in all of the photos are about 1 – 2 mm long. They are all very well formed.
FOV in the first pair of photos is 2.2 x 2.9 mm. The crystals are about 1 mm long.
The second pair of photos (FOV 6.8 x 4.6 mm) is a broader view of these same crystals and others. The largest crystal is ca 2.0 mm.
FOV in the third pair of photos is 4.4 x 4.7 mm. The largest crystal is about 1.5 mm.
The next photo (FOV 3.6 x 2.4 mm) shows manganoneptunite crystals clustered about a pseudomorph, probably after petersenite-(Ce) or rémondite-(Ce). The interiors of other such PSMs are filled with grainy ancylite. (But there are not many on the specimen.)
The next photo (FOV 2.3 x 3.4 mm) shows one of the unidentified amphiboles. The analyst (very tentatively) suggested a hornblende. But most, if not all, hornblende at MSH is “magnesio-”, and there is no Mg in the scan. To me, the crystals look like arfvedsonite. Moreover, from past experience with other minerals scanned on this equipment, I know that it is about twice as sensitive to Fe as to Si. The Fe:Si peak height ratio in the scan (#322) is 5:4, which, allowing for the difference in sensitivity, corresponds to an “actual” Fe:Si ratio of 5:8 – precisely what one expects for arfvedsonite. Of course such calculations are strictly illegal for qualitative EDS scans such as these. Well – WDS is totally impractical for something like this, so this will have to do. And I’m not claiming anything specific in any case. Just having some fun with funny numbers.
It is true that there is a lot of stuff in the scans that doesn’t “belong” in arfvedsonite. But the microprobe scans published in Mandariono’s “Monteregian Treasures”, show significant amounts of each of them: Al, K, Ca, Ti, Mn. Only the Ti peak is really unusual. But “titanian agerine” is known from MSH, so why not “titanian arfvedsonite”?
The last close-up photo (FOV 2.3 x 3.3 mm) is a slightly different view of this same amphibole. The encrustation is more evident in this photo. As to what the crust is, you can ponder the EDS scan (#322B). I don’t know anything at MSH that is a potential match. Perhaps it is just “mud” – i.e. a mixture.
Single item shipping weight (no case) is 7.9 oz. For shipments outside the USA, any additional items will bump the shipping weight to the next postage “band”. This band is good up to 32 oz, but costs $6.50 more to Canada and $9.50 more to most other destinations.
Within the USA, postage increases by about $0.20 per ounce. Above 13 oz (up to 16 oz), I will use Priority Mail (ca $9.25 including packing – varies by destination). Above 16 oz the rate is about $13.75.
