Main Ridge Gold Mine (Jamaica)

 AusJam Mining Ltd


Central Jamaica, Parish of Clarendon, approximately 5 km west of Pennants on Highway B3.

Regional Geological setting:

Located within the Central Inlier consisting of an Upper Cretaceous volcano-sedimentary sequence surrounded by Tertiary limestone.

Target Metals:

Gold, in low-sulphidation epithermal quartz-carbonate Au-Ag setting

Mineralisation Setting:

The mine sequence is within the Bullhead Formation (calc-alkaline andesite (± dacite) to basalt composition with minor flows and fine sediments). Mineralisation is controlled by the east-west, steeply south dipping Bennett Fault.

Gold is associated with stockwork quartz supporting a volcaniclastic breccia.

Deposit Grade & Size:

Typical grades are from 5 to 8 gm/tonne gold, with average mine head grade of 7 gm/tonne.  The west zone has more erratic grades (to 120 gm/t gold) and head grade varying from 5 to 15 gm/t.

Exploration History:

BHP Minerals International Exploration, Inc (BHP) 1989 – 1993
Orvana from 1993 – 1996
95,725 tonnes at 9.01 g/t containing 27,739 oz gold to a pit floor at 310m RL

Exploration Tools & Methodology:

Geological mapping of pit
Review of previous drill data
Create new mineralisation model based on pit observations
Create OBM and constrain to mineralisation model
Calculate new resource, and compare to production history
Global (pre-mining) resource of 178,000 tonnes @ 3.7 gm/t for 21,000 oz gold to 300m RL – reconciled with production.

Resource Potential:

Much unexplored ground remaining.
Regional potential for porphyry style Cu-Au deposits.