NI 43-101 Technical report, Surface diamond drilling ... - Iamgold

R a r e E a r t h E l e m e n t E x p l o r a t i o n P r o g r a m M a r c h - 2 0 1 3
W i n t e r - S u m m e r 2 0 1 2 P a g e | 23
Late, 1-3 mm wide, partially to completely filled veins, containing euhedral calcite, barite
and fluorite cut across the brecciated and also across the unbrecciated dolomitite (Fortin,
1977; Fournier, 1993).
The uppermost 60 m of the REE Zone were heavily weathered to an orange or red color as a
result of exposure of the carbonatite to the atmosphere prior to deposition of the Trenton
limestone (Figure 7). At depth, red staining of carbonates is a more local phenomenon, and
the characteristics of the breccia are easier to recognize (Dénommé, 1985; Fournier, 1993).
At the microscopic scale (Fournier, 1993), dolomitite clasts range from an Mg-rich variety to
a more iron-rich variety containing significant manganese. They make up a solid solution
between dolomitite and ankerite, but some crystals of magnesian siderite are also found.
The carbonates cement of the breccia varies from ferroan dolomite to ankerite but is poorer in
Ca than the associated clasts.
The chlorite is brownish colored, iron-rich and locally comprises up to 20% of the rock by
volume in interstices between carbonates grains. This contrasts with the Mg-rich, greenish
variety, which replaced phlogopite in the Niobium Zone (Fournier, 1993).
The apatite, which classifies as fluorapatite, has higher fluorine content and a more
stoichiometric phosphorous content in the REE zone than in the Niobium zone. However, the
REE content of apatite from the two zones does not differ significantly.
The principal REE minerals are fluorocarbonates and take the form of needles in radiating
bundles or in parallel growth and measure a few microns in diametre and up to 20 micron in
length. REE fluorocarbonates minerals are concentrated mainly in the breccia matrix where
they are associated with either chlorite, hematite, dolomite or organic matter.
The monazite [(REE,Th) PO 4 ] occurs as irregular, micron size grains spatially associated
with parisite but enclosed in the bastnaesite; and the thorite (ThSiO 4 ) as micron size, opaque,
grains set in either chlorite or organic matter.
The oxide minerals in the REE zone, the hematite, is found either as discrete fine (