Pyenglong Ruby Deposited

Drilling

The campaign was focused on defining the breccia zones indicated by surface works such as pitting, trenching, and aditting. Joy 12B and Long Year 24 dirll ridge were used in Pyenglong Project. Ninety five drill holes have been completed in the area. The first was initiated on the 8^th March, 1991. It involved slightly random holes around the open-pit mining area and 30.4 m (100 feet) spaced squar-grid holes along the breccias zone to the northeast. There were total of 95 holes and drill site were 70 sites of which 55 were inclined and 40 were vertical in October, 1995. Total depths are 4295.6 m. All are shallow, the deepest hole is 85 m I apparent thickness, and the shallowest one is only 10.6 m. Among them 43 holes hit the breccias zone or zones varying from 0.18m to 19.8 m in thickness including four holes with ruby in the breccias core.

Breccia Zone

In general, within the Mogok stone track, ruby occurs crystalline limestone, alaskite and pegmatite.

Sapphire occurs in alaskite, pegmatite and syenite. The style of major ruby mineralization at Penglong is totally different from those of the Mogok area because it is all in a breccias zone parallel to regional trend of the rocks. Pyenglong is totally different from Mogok area.

In mining area, major high-angle fault striking NNE-SSW and cross faults running N-S and NW-SE are well preserved at the open-pit mine. The strike of the breccias zone, running 60º along upstream of a small creek, varies from 1.5 m to 3 m and it widens to about 60 m to the northeast. Total length of breccias is ~480 m, forming a dyke-like body and sills and veinlets along fractures cutting through the metamorphic rocks and granites. Individual thickness of gem bearing zone are various from a few cm to 10m but not all breccias are gem-bearing; those with sandy matrix and felsic coloured breccias in particular are barren.

Gem bearing breccia is black, reddish brown and greenish yellow in colour soft clay matrix. Sometimes carbonaceous breccia where the rubies are hosted, no ruby has been fournd in the clasts of the breccias. The comparative of mica in the breccias is a prominent feature in the Penglong ruby mineralization. The most favorable characteristics of the breccia for hosting rubies are the abundance of mica and chalcedonic slabs and greenish yellow colouring of the breccia. When sun-dried the breccia hardened and its colour changes to whitish grey. Another informative feature is the scarcity of ruby in the breccias close to the clacsilicate and alaskite, where there are more spinels and more sapphire than ruby. The clasts of breccias are various metamorphic rocks, biotite granite, vein quartz, vuggy quartz, chalcedonic slabs and very few red chert. Doment clasts are quartzite, less than 2 cm to more than 1 m in length and granite, less than 2 cm to 0.3 m length. The associated minerals in the breccias are mica, talc, graphite, pink and green garnets, black and green tourmalines, limestone, pyrite and black, purple and pink spinels some which are coated with talc. According to the heavy mineral analysis, hematite is very common and zircon, rutile and sphene are also detected in ruby-bearing breccias. Under the microscope, most micas examined ate phlogophite and the others are muscovite and brittle mica called margarite. Some muscovites are green due to chlorization. Serpentine is associated with steartization structures and iron oxide is formed as the common opaque mineral. Two kind of titanium minerals, rutile and anatase, are also detected. The combination of very high relief, low to moderate birefringence, and the occurrence of twin lamellae are red coloured with rutile and zircon inclusions. The noticeable feature is the coating of ruby by serpentine, talc and margarite.

Origin of the ruby in the Pyenglong

The origin of the Mogok ruby has two alternative ideas 1. Contact metamorphism and 2. Regional metamorphism. In the Mogok area rubies are set in the marbles which from bands and lenses interbedded with gneisses. But at Pyenglong open-pit mining area, rubies are found only in breccias associated with country rock fragments, pegmatitic material some minerals mentioned above. The abundance of ruby is correlated with phlogopite mica, flattened cherty slabs and porous, low density, non clceraceous white coloured rock fragments which seem to be decalcified marble and it may be the original host rock of the rubies. This idea is supported by the presence of ruby bearing coarse-grained white marble exposed at the head of a small creek at about 250 meters lower level and 1 km to south of main pit.

Production

There were underground mining at first. Later, there was open pit mining. December, 1989 to end of March 1996, that mine produced 48,231 tons of ore, were mined out, yielding 540,550 carats of rubies including 80,997.06 carats of gem qualities.

Produce From; A New Rubby Deposite in Myanmar, its Exploration and Mining (Nyunt Htay, 19 Jun, 2010).