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Country of Origin: Nigeria
Mining Location: Angwan Doka Mine, Keffi, Nasarawa State
Located on a small hill south-east of Keffi, the Angwan Doka pegmatite has been mined for the past last 30 years.
Doka is a complex pegmatite with 5 different mineralization zones, some of them containing pockets of tourmalines. The kilometer-long pegmatite is several meters in thickness and dips steeply into the ground. During the early days of mining at Doka, miners had the dig pits less than a meter deep to reach the tourmaline-bearing parts of the pegmatite.
Nowadays, these easily accessible areas are mined out and the pits are much deeper, up to 16 meters. The deeper parts of the pegmatite have not been weathered by erosion; thus, the miners must use drills and explosives to reach the tourmaline pockets.
Production from Doka is quite irregular, as it is often the case in pegmatite mining. A major strike happened in 2017 and 2018 when the miners hit several pockets containing a large number of high quality, clean tourmalines.
The tourmaline crystals found at Doka are typically up to a few centimeters tall, with an open c axis and possess clean cores under the crystal skin.
Doka is famous first and foremost for its beautiful pink tourmalines, but other highly pleasant shades are produced such as peach, autumn (a bi- or tri-color blend of golden yellow, pink, and green) and rarely canary yellow.