The hellandite group mineral is the little off-white “fungus” on striated, colorless, pectolite. This mineral was formerly thought to be tadzhikite-(Ce), but in the absence of single crystal XRD, it is not possible to say more than “hellandite group”. (See the information page for tadzhikite-(Ce) on the Mindat species list for MSH.) In any case, it is a very uncommon mineral at MSH.
The “hellandite” can be seen most clearly in the first pair of photos (FOV 2.4 x 3.8 mm). Here the “hellandite” aggregate is at right of center and spans ca 0.4 mm. The tiny glassy crystals are apopohyllite. The brown/bronzy stuff is ubiquitous in MSH cavities. Often it is something amorphous, but supposedly Fe/Mn oxides and other things occur.
The “hellandite” is not very obvious in the second pair of photos (FOV 6.4 x 4.4 mm). It is the 0.35 mm blob in the center of the pectolite crystal at top. By comparison, the main pectolite crystal is about 5 mm long. These photos are mostly about the pectolite, which is very pretty under the scope.
The third pair of photos (FOV 4.3 x 6.7 mm shows four aggregates of “hellandite” to ca 0.35 mm, but at the scale of these photos hey are, again, a bit hard to spot – look near center-right at the base of the pectolite crystals. The pectolite terminations are a bit fuzzy, but not bad for pectolite. The larger pectolite crystal in the center of these photos is ca 5 mm long.
The fourth pair of photos (FOV 2.2 x 3.3 mm) shows another “hellandite” aggregate spanning 0.35 mm. It sits on a larger, transparent, pectolite crystal. Other pectolite crystasl interrupted growth at the top.
There are a few other “hellandite” aggregates on the specimen, but they look much the same as the others. There is also a bit of dark brown phlogopite – nothing special.
Note: The specimen consists of two parts that are only loosely connected. I’m not sure what holds the parts together, but they can be moved a bit relative to one another. All of the “hellandite” and all of the prettiest pectolite crystals are on the “top” part. The “bottom” part acts as a natural “mount”. Should the two pieces become separated, it would be no big loss. I will ship it “as is”. If you want to keep the parts together, just be careful when unwrapping.
Single item (small box) shipping weight 2.0 oz. For shipments 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. If you wish to keep an “open box”, let me know.
For shipments within the USA, there is a nominal increase of about $0.20 for each additional ounce. Above 13 oz I will use “own box” Priority Mail ($9.25).
If desired, this could be sent in a padded envelope, but the postage is the same.
