This specimen is ex Ron Waddell. Ron’s label says that the “britholite” was ID by Dr. G. Y. Chao in August 1988, i.e. 6 years before Dr. Chao published the description of fluorbritholite-(Ce) (for which MSH is the TL) in 1994. Detailed chemistry – sufficient to distinguish between F and OH – was probably not done, but if it was, that is not mentioned. So this could be either britholite-(Ce) or fluorbritholite-(Ce).

According to Horváth et al (Min Rec 1990; Lapis & Rivista 2000), both britholites are found only in the sodalite xenolith environment and are very rare there. Crystals are mostly inconspicuous, colorless to pale pink, and embedded in sodalite. Radiating sprays in tiny open cavities – such as the one in the photo - are very rare. However Dr. Chao’s paper describing fluorbritholite-(Ce) states that the mineral occurs in “nepheline syenite, marble xenoliths, sodalite syenite xenoliths and pegmatite dikes”. 

In any cas, the matrix of Ron’s specimen does appear to be sodalite xenolith with 50% or more consisting of brightly fluorescent sodalite along with a small area of (probable) ussingite).

FOV in the first photo is 2.1 x 2.8 mm. The britholite crystals are ca 1.8 mm long, which is near the upper limit reported by Horváth.

The photo (FOV 2.6 x 2.0 mm) is essentially the same view, turned sideways. (This is an older photo. The color balance is probably a bit too blue.)

I don’t know what the yellowish flakes are – some appear to be hexagonal with some sort of encrustation. According to Ron’s label, there is also “gmelinite” and natrolite, but these are in another cavity. By today’s standards, they are tiny and insignificant – not photo worthy.

Single item shipping weight is 3.9 oz (110 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 ($9.25 including packing).