A big surprise at the Denver 2009 show was the appearance of what were widely being called among the world's best demantoid garnets; and in smaller numbers what are absolutely the world's best examples, without compare, of the rare topazolite garnet variety. These come from a remote deposit that is quite literally situated in a tidal-flooded mangrove swamp, near the town of Nosy Faly in Madagascar. Within a short time of their discovery, they had come to the attention of Dr. Federico Pezzotta of the Natural History Museum of Milano (after whom the new Madagascan beryl species Pezzottaite was named), an expert on both mining and the mineralogy of Madagascar. Dr. Pezzotta soon was able to facilitate the valuation and legal export of most of this material. In Tucson, he gave a talk on this locality, and the difficulties of mining there, from which the below information is taken with his permission. As well, through his sources I was able to obtain a very good mixed lot of specimens from this find, including both Demantoid and Topazolite garnets, in a variety of size and price points. ALL SPECIMENS WERE HAND-SELECTED FOR ME AT THE MINES, AND ARE (UNLIKE MOST) GENERALLY PRISTINE AND FREE OF DAMAGE!

Google Earth views of the region: at ocean's edge

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Dr. Federico Pezzotta on location...

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The deposit is literally situated in a mangrove swamp, that floods each afternoon at high tide. The waters come in so fast, that I am told you have only a few minutes to clear the mining holes once it starts to come up from the ocean. And, the miners work til the last moment, to gain precious rock to sort later. Dr. Pezzotta has photos (below) showing both low tide with the working pits and their straw mat dividers; and then showing a higher rising tide...but could not ever get a shot at full tide because everybody must leave to walk 1.5 kilometers to "higher ground" ( - thus, nobody is around to take the photo at sunset when the tide is highest and completely covers all workings, huts, and barriers).

Low Tide vs. Rising Tide

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The garnet-bearing region on its surface measures about 400 x 400 meters, and is a hard rock to mine in. Nothing is on the surface, and the deposit was discovered completely by accident when locals found shards of garnet in the sections of rock exposed by ocean erosion lower down towards the coast. In this small region, now nearly completely denuded of its original mangrove covering, Dr. Pezzotta counted approximately 800 INDIVIDUAL mining holes, dug to various depths and without any regard for geology or mineralogy. They are dug quite literally at random and some people will dig for days to go down to depths (with HAND TOOLS only!), even after being advised that the rock may not be under them. 800 holes requires 800 teams of diggers, haulers, and sorters; and so you can imagine the crowd during working hours of some 2000-2500 people in this swamp, all flowing in and out with the tides of water. To reach the garnet layer, the miners have to dig straight down (literally, in vertical, rope "hanging seats"), 10-20 meters below the surface. When they hit garnet-bearing rock, they then branch sideways, each miner's group making their own tunnels where they wish and without apparent regard for the gradually honeycombing structure of the rock caused by other mining teams above, beside, and below them. Each "mining group" is actually a family or group of friends, working in teams to do this digging in a rush during the daylight hours, and when the water allows. Each team must start the day when the tide recedes, around 4 AM (after walking 2 kilometers from town), by spending 4-6 hours pumping water manually through a series of pipes and tubes to access their holes.

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Then, they have several hours to frantically dig - hauling buckets out as fast as they can, for later sorting in the tidal pools by other team members. For the very ambitious workers, they all haul buckets and get to the sorting after hours - after carrying the heavy buckets to the high tide line 1.5 kilometers away. The problem is, obviously, that the holes fill each night with the tide. Between the tides and rainwater filling the holes, digging here is absolutely impossible in the rainy season and so all mining has ceased for the moment. It is an open question of whether it will be economical (and safe) to continue digging when the drier season of 2010 comes around. Given the conditions, the working with hand tools in small one-man holes, and the urgency of digging quickly, it is easy to see why so few perfect specimens are obtained. Most of what is recovered are smashed crystals simply hacked off the rock for any quick faceting value that can be yielded from the buyers in the wholesale gem trade. <

NOTE ON GEOLOGY: This deposit is unique. Studies by Dr. Pezzotta and his former graduate student Dr. Emanuele Marini, have confirmed that the main body of sedimentary rock here has been altered over geological time to a fine-grained garnet. The seemingly limestone matrix is so hard and strong for a reason - it is not limestone!

Per Dr. Marini: The matrix is mainly sedimentary rock (sandstone) metamorphised by lamprofiric dikes cross cutting the sedimentary deposit. On many matrix you see micricristalline garnet or the relict structure of the sedimentary rock. On few specimens you can see fossils. The demantoides formed in the fractures of the sedimentary rocks and yes, sometimes the matrix is micro-xls of demantoid with a growth of larger xls on them. Metasomatism is a serie of chemical reactions that bring a partial recrystallization with variation of its compounds: so, we can consider the demantoides a product of the metamorphism inducted by the intrusions of the lamprofiric dikes in the sedimentary rocks. All the garnets crystallized in the fractures are andradite, the Titanium member of the series. In some matrix closeups, the whiter style, you can observe some small sub-mm creamy xls. Actually these are andradite garnet as well, but with a conspicuous grossular component. The only associations are some quartz and (very rare and unusual!), stilbite.

Garnet pseudomorph after Limestone Fossil of brachiopod!
(Federico Pezzotta specimen and photo)

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