Phillipsite and chabazite are both rare minerals at MSH, except in the Poudrette pegmatite, where chabazite was fairly common, and phillipsite was moderately common. But this specimen is from a marble xenolith (or perhaps a breccia). According to the MSH rarity tables of Horváth et al (Lapis, Rivista July/Aug 2000), these two minerals are rare to non-existent in those environments. No doubt these tables are out of date. Nonetheless this is very rare stuff for MSH. Moreover, the phillipsite crystals, though small (<= 1.0 mm), are untwined singles and are very nicely formed. Some are doubly terminated.
Both the phillipsite and chabazite were analyzed via EDS. (See the “Analysis” tab.). For comments on the IDS, see after the photo descriptions.
The first photo (FOV 1.5 x 1.6 mm) shows a nice cluster of phillipsite crystals, each ca 0.7 mm long. But this photo was made using the equivalent of about 60X. You will need at least 20-30X to view these crystals properly. (However, they are clear enough even at 15X.)
The next pair of photos (FOV 2.1 x 2.7 mm) shows more phillipsite. The doubly terminated crystal at top center is 1 mm long.
The next pair of photos (FOV 1.25 x 1.75 mm) is an extreme close-up of a single crystal of chabazite-Na (0.5 mm) and a single crystal of phillipsite (0.55 mm). (There are more chabazite crystals in the center, seen more or less edge-on.)
A somewhat similar arrangement of chabazite and phillipsite is shown in the next pair of photos (FOV 1.1 x 1.65 mm). Here the chabazite (0.4 mm) is twinned in a characteristic way. The phillipsite is ca o.5 mm long.
The final pair of close-up photos (FOV 2.3 x 3.3 mm) is a somewhat broader view showing several chabazite twins (0.55 mm) and phillipsite crystals ca 0.6 mm. There are many more such crystals on the specimen.
Regarding the IDs:
In the case of the phillipsite, the scan taken in conjunction with the habit, is a pretty definitive. However, even though the “K” peak in the scan is much higher than the “Na” peak, it is not possible to say with certainty whether this is phillipsite-K or phillipsite-Na., because this is only a qualitative scan and the equipment is nearly insensitive to Na. Both species are found at MSH, with phillipsite-Na being much more common. (In that regard, the abovementioned tables are known to be in error.) But in the absence of WDS, I hesitate to call this either phillipsite-Na or phillipsite-K.
The EDS scan for the chabazite (#222) is very similar to that for a well-verified specimen of chabazite-Na. I have included this scan (#102) for reference. If anything, the “K” peak in scan #102 is even higher relative to Si than the one in scan #222. But despite the apparent abundance of “K”, scan #102 is for chabazite-Na. Chabazite-K has not even been reported from MSH. The only other chabazite at MSH is chabazite-Ca. Since there is no Ca in scan #222, I feel it is reasonable to call this chabazite-Na. Moreover, the habit is typical of chabazite-Na at MSH.
Single item shipping weight (with TN case) is 3.2 oz (90 g). For shipments outside the USA, up to a total weight < 8 oz (225g), this can be combined with items from this or other auctions for the same postage.
Within the USA, postage increases by about $0.20 per ounce. Above 13 oz, I will use Priority Mail (ca $9.25 including packing – varies by destination).
