Apui_geology and gold next to BBX, page-7

Cool. That Teles Pires Intrusive Suite gabbro (also found at Ema and Tres) is the key.

From http://www.bbxminerals.com.au/wp-content/uploads/Juma_Geo_Opinion.pdf :

Geology and Mineralisation

The volcanic rocks in the Eldorado do Juma were considered by Companhia de Pesquisa de Recursos Mineirais (CPRM) to be part of the Colider Group and the sediments to the Beneficiente Group. Locally at Eldorado do Juma, rocks have undergone hydrothermal brecciation, forming strong stockwork mineralisation, silicification, argillic and sericite alteration. Chemical and isotopic data completed by CPRM show that this sequence is dated around 1,757Ma +/- 16 Ma (U-Pb zircon) which correlates it with the Teles Pires Suite.

Gold is typically located along the vertical joints (at least 3 mineralised joint/fracture planes were noted by Amazon Geoservices) and also along the bedding surfaces. This suggests low pressure hydrothermal mineralisation. Strong stockwork veining is present in the Gabbro unit that is found at the base of the sediment and intercalated volcanic package. This Gabbro has been identified over 4km of strike and is highly likely the source to the hydrothermal fluids that have deposited the gold along fractures and veins in the sediments.

Exploration Potential

No systematic reportable exploration has ever been completed on the Eldorado do Juma project. It was discovered in 2006. The Cooperative group Cooperjuma has reported between 50,000oz and 100,000oz of gold has been produced. Amazon Geoservices is unable to confirm this figure. Key observations that support the high exploration potential are below:

• The Garimpo workings can be traced intermittently over 4km strike and are aligned with the interpreted rim of a caldera feature (8km in diameter). Continual panning by Amazon Geoservices on the Garimpo pits produced coarse gold.
• The Garimpeiros have partially mined only the mineralised intercalated sediments and volcanic, which is 20-30m thick and up to 200m wide. This soft free dig unit is underlain (and was fed) by an intrusive Gabbro?. The intrusive has strongly developed stockwork veining. This intrusive represents a prospective target.
• Significant tailings remain from the historical mining. Current extractive practices are basic with < 50% of the contained gold recovered. Reprocessing the tailings could generate early cash flow for the project if sufficient tonnes and grade are defined.
• BBX have secured over 80% of this Caldera structure which presents a large area of untested prospective ground.
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Looks like the whole tenement package they're trying to flog is in the new national park. :(