Tonga soa Madagascar: The Phenakites of Sahanivotra

a very nice example of the new Phenakite
In December 2015, my American friend Mike Shannon and I purchased what we were told were rhodicite crystals at the Antsirabe mineral market. At first glance, this seemed to be correct, only a day later I had my first doubts. Some of the crystals just couldn't be of the cubic system. The Mohs' hardness seemed fine, but the paragenesis made me even more suspicious: Rhodizite with magnetite was previously unknown to me. Mike and I had a long discussion and we came to the conclusion that it was probably phenakite. Back in Germany, the mineral was X-rayed (thankfully done by Herrrn Belendorff, Münster) and the result was clear: phenakite.
Even after our discussion, we decided to acquire as much of the material as possible. The find spot was described to us as very inaccessible, 8 hours walk from Ibity somewhere in the mountains, no overnight accommodations, etc.
The, as we soon knew, phenakite crystals occur in a matrix of smoky quartz and magnetite, we rarely found greenish beryl in poorly formed crystals.
large group of phenakite crystals on smoky quartz, partly orange in colour
Most of the crystals are white, sometimes completely clear, i.e. facetable, but sometimes very nice orange, probably due to FeOOH. The size of the crystals ranges from a few millimeters to as much as 6 cm. Only a small portion of the crystals are complete. Since there are hardly any drusen or cavities in the matrix, most of the crystals are somewhat damaged.
The following year, 2016, I was able to visit the deposit with the permission of the President of the Antsirabes Association of Mineral Dealers (for 3 years foreigners have been generally forbidden from accessing the mineral deposits). to my over-
On to the pheankit deposit with a small river trip on the Manandona River
surprisingly it wasn't 8 hours. The deposit is located near the town of Sahanivotra in the Manandona Valley, about 25 km south of Antsirabe. This included a small boat trip on the Manandona River with some
arrived, now we continued on foot
Accompaniment: the owner of the small mine, the president of the dealers and some children. It was a pleasant walk up a small valley, until after a few kilometers across country up a mountain
at the top of the mountain in the middle of the picture by the trees is the small mine
went up. In a small stream valley lies the deposit that has provided a lot of beautiful crystals. The creek, as the owner informed me, had the phenakite dike during a violent cyclone
This is what a Madagascar deposit can look like: many good phenakites were found here
washed free. When the above photo was taken, the men had been working there for 4 months (working is not possible during the rainy season from November to April). Unfortunately, nothing could be learned from the regional geology during a short stay, and a short excursion in the creek bed did not yield any new insights. The vegetation is just too dense. The occurence
the main adit that yielded most of the phenakite crystals
is limited to a small pegmatite dike accessed by a short adit. There were hardly any phenakites to be seen at the working face, obviously the tiny deposits had already ended there. Work was done with a few men, all in
                        lateral inquiries yielded no phenakites
Handwork. The hands of the ungloved workers looked suitably scarred, the sharp quartz had carved deep cuts into them.

in the narrow tunnel, the owner and the reporter
We parted as friends and I promised the men I would support them in the future.
The following year, 2017, the small outcrop completely collapsed from the heavy rains, and the men gave up trying to work it again. In the meantime they have been working again since April 2018, our company is now financing the further work in the hope of more phenakites.
 veloma (see you soon), I said goodbye to the owner of the small mine

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