.
Location: 46 km E from Dom Pedrito, Brazil
Level 12, 680 George StreetSydneyNew South Wales, Australia2000
Stay on top of the latest gold discoveries. Examine the latest updates on drilling outcomes spanning various commodities.
Mining scale, mining and mill throughput capaciites.Full profiles of select mines and projects.
Shaft depth, mining scale, backfill type and mill throughput data.Full profiles of select mines and projects.
Equipment type, model, size and quantity.Full profiles of select mines and projects.
Camp size, mine location and contacts.Full profiles of select mines and projects.
- subscription is required.
The Três Estradas deposit consists of an elongated carbonatite intrusion with a strike of 50° to 60° similar to that of the Cerro dos Cabritos Fault. Shear sense indicators suggest a sinistral sense of motion along this fault. The carbonatite and amphibolite form a tightly folded sequence with limbs dipping steeply from 70° to vertical (90°). The surface expression of the intrusion is approximately 2.5 km along strike with a width of approximately 300m.With the exception of meta-syenite along its northeast and southeast boundaries, the carbonatite is surrounded by biotite gneiss of the SMCGC. The carbonatite is tightly folded and strongly foliated, resulting in a well-developed gneissic texture. Locally, abundant subparallel quartz veins are present resulting in elevated topographic ridges as the quartz is more resistant to weathering than the surrounding country rock. These veins range from a few centimetres to a couple of meters in width and can be up to 300m long. Also flanking the carbonatite is a minor unit of meta-tonalite with intercalated meta-carbonatite and amphibolite. The unit is characterized by gneissic banding, a grey-green colour on weathered surfaces and a recrystallized granular texture.The carbonatite intrusion is characterized by varying amounts of amphibolite. Amphibolite and carbonatite bands alternate on a meter-to-millimeter-scale. Phosphate mineralization is disseminated and contained in apatite crystals throughout the carbonatite intrusion and in the overlying saprolite. Aguia’s current interpretation suggests that the carbonatite intrusion is formed from three magmatic phases that were later metamorphosed to an amphibolite assemblage.Mineralization Phosphate mineralization, occurring as the mineral apatite (Ca5(PO4)3(F,Cl,OH)), is the primary mineralization of economic interest at Tres Estradas. Apatite is the only phosphate-bearing mineral occurring in the carbonatites. At Tres Estradas, phosphate mineralization occurs in both fresh and weathered metacarbonatite and amphibolite. Phosphate also becomes highly enriched in the overlying saprolite. Apatite is a common accessory mineral in carbonatite and ultramafic igneous deposits. The apatite forms submillimeter-sized, subhedral to euhedral crystals that are disseminated throughout the groundmass. Apatite crystals are pale in color, requiring care when observing fresh, unaltered rock. In weathered rock, apatite is resistive to weathering relative to the carbonate matrix, making then easier to identify with a hand lens. Calcite is the primary carbonate mineral at Tres Estradas and accounts for approximately 60% of the mass of the carbonatite. Carbonatites are typically complex, multi-phase intrusions with subsequent phases showing signs of fractionation. Apatite along with anatase and magnetite tends to be dominant in early phases of an intrusion while later phases of intrusion tend to be dominated by higher concentrations of niobium and rare-earth elements. Aguia geologists have noted up to three distinct phases within the cores from the Tres Estradas Phosphate Project.DimensionsMineralization has an approximate strike length of 2,400m and extends to a depth of 370m below surface. Mineralized zones range in thickness from 5m to 100m.
