Gemstones

Project Name:	LAKE MANYARA MOROGORO		Click on map to enlarge
Location:	Lake Manyara
	The properties are located within the Karatu District in the Arusha region, approximately 12km north of Magara town and 2.5km from the western shore of Lake Manyara.
	Morogoro
	The licence is located at Matombo, in Morogoro District, approximately 25km southeast of Morogoro.
Area:	Lake Manyara	5.88km2
	Morogoro	2.77km2
	The emerald licences are valid for an initial period of 10 years and confer the holder the right to prospect for and mine gemstones. Furthermore, all these licences can be extended for an additional 10 years.

Access:

Lake Manyara

The licence areas can be accessed by dirt tracks that lead off the main Arusha - Dodoma tarmac road, towards Magara, along the south margin of Lake Manyara.

Morogoro

Access to the licence is via a dirt road running south from the main Dar es Salaam - Dodoma road at Morogoro. Dar Es Salaam is 200km to the east. The licence is located at Matombo, in Morogoro District.

Fresh Elephant Droppings on the road to Lake Manyara Emerald Licences

Geology:

Lake Manyara Emeralds

The host rock for the emeralds, and other gemstones, of the Lake Manyara area are largely metamorphic units of the Precambrian-aged Usagaran System. These units typically comprise felsic schists and biotite-actinolite schists with small pegmatitic veins common.

Emeralds and alexandrite are commonly associated with the contact zones between clear quartz vein and biotite-actinolite schists. Gemstones have also been recorded as occurring at the contact between thin veinlets of granite/syenite and biotite-actinolite schist.

NE- SW biotite-filled splay fault that contains the Emerald at Lake Manyana with one of the Artisanal Miners

Geological mapping indicates a series of large scale, northeast striking shear zones that trend parallel to sub-parallel to faults and as splays off the fault trend with east-west orientations (reidal shears). Emeralds and other precious minerals occur within boudins, shears and additional fractures within these structures, which acted as fluid conduits.

Emerald & Gemstone Mining in Tanzania

The Lake Manyara emerald field has had a long history dating back to 1970, of being explored and worked, particularly near the Maji Moto hot springs, which occur some 4km to the north of the licence area. Between July 1970 and April 1972 more than 231,877 grams of emeralds were produced. After this mining activity in the area was nationalized, leading to a drop in production and a lack of any formal production statistics.

An estimated 550,000 artisanal miners are involved in the production of coloured gemstones, diamonds, gold and other commodities within Tanzania according to the USGS 2006 Minerals Yearbook. These artisanal miners account for most of the gemstone production but these production levels may be expected to drop as deposits become deeper and require capital investment and mechanization.

  

Heading to artisanal workings

Lake Manyara Emeralds and Alexndrite (top right)

The Manyara deposit is known for a variety of gemstone other than emeralds, including alexandrite, ruby, garnet and spinet.  Emeralds and gemstones from the Manyara region are described as brilliant with a vivid luster and high transparency (Gubelin 1974). The alexandrite displays the classic “alexandrite effect” whereby it displays a bluish-green hue in daylight and a raspberry colour in incandescent light.  According to Gubelin, gemstones from the Manyara region are of exceptional gem quality producing high grade stones of up to 5 carats (source: The Emerald Deposit at Lake Manyara; The Lapidary Journal 5, 338-347 Gubelin).