Aquamarine is the blue variety of beryl. Aquamarine is found in pegmatites. A pegmatite is a lens of mineral bearing rock that was formed when the rocks cooled out of the magma. An interesting fact that a miner told me recently is that they look for a certain type of tree as an indication that there might be a pegmatite there.
Not all pegamtites have precious stones in them. The miners look for 3 things. Feldspar, mica and quartz. When you find the quartz you might get the aqua. The quartz veins inside these pegmatites can be huge. Several tons in size and this quartz is hard. Have you ever heard the saying “as hard as rock” Well it is as hard as that. A chisel will jump off the quartz without even denting it. You need a sledgehammer and you need to hit the quartz several time in the same spot to get chunks to chip off. Inside the quartz you might suddenly come upon the aquamarine imbedded inside. Once the aquamarine crystal is removed you will have a six sided cavity. All aquamarine forms as a hexagonal crystal with usually a flat termination.
When you find one of these pegmatites you will find that the first few meters on the surface has been exposed to a lot of weathering. The crystals in this layer is soft and just falls apart. You have to go quite deep to get the gem kind and the deeper you go the tougher it gets. It is almost like playing a One arm Bandit. You never know if the gems will be found in the next layer. A miner friend of mine told me how he once found an enormous pocket of aquamarine. He said the pocket was almost 800 mm in size. The opened the pocket and saw large crystals criss-crossing each other. You might get pockets like these or crystals imbedded in the host rock. If you get a gem pocket all your hard work was worthwhile. You can then extract the crystals to be sold as specimens for collectors or remove them to be cut into gems. The deep blue ones are the most sought after and fetches the highest price.
Most of this mining is done by small scale miners with artisanal tools. The mine owner promises them a share in the profits once a pocket is found, otherwise they just work for food and lodging. In some areas in the world you will find these pegamtites amongst the poorest people in the world. I have just been to Malawi and have visited several of these small mines. Malawi is the 160th poorest country in the world and many fine pegmatites are found in the north of this friendly country. Miners can sometimes work for a whole year and not get any crystals that they can sell. Imagine this, the hope, the dreams and the toil for nothing. But they all know somebody who have bought a truck or who have built a new house out of his proceeds and that is why they continue to dig.
In Africa most of the digging is done by small miners that live in the area. This is the only way that stones often see the light of day. Large mines uses machinery that cost millions of Dollars and they have to first do a feasibility study to determine if the mine will support the outlay of millions of $’s. Most pegmatites are too small to justify this cost. The small miner in comparison makes a contract with the workers that they will get paid when the goods have been bought. The mine owner then just buy food and provide the tools and shelter for the miners. They will then all share in the proceeds. If there is no production they will not see any money. My personal experience buying gems in Africa is that the miners will stop mining if they get money in advance. They will first use up all the money and then they will start mining.
When they find gem grade there will be a chain of supply. Somebody in town will act as a middle man and they will buy the gems at a fairly low price off the miners. This middle man will sell it to a West African who will have ‘brothers’ in Hong Kong or Bangkok. The stones will now make their way to the Far East where it will be cut into a gemstone. So next time you look at your aquamarine just imagine where it comes from....