Texas Silver Project
The Texas district is a key project in Thomson’s New England Fold Belt (NEFB) Hub and Spoke central processing strategy, where Thomson has the objective of bringing together a series of deposits that can feed a central processing facility. The Company has recently published JORC 2012 Mineral Resource Estimates for the Silver Spur, Twin Hills and Mt Gunyan deposits for an aggregate of 19.5 Moz AgEq at 54 g/t AgEq.
The Thomson Twin Hills MRE block modelling highlights that the resource is open to depth in several areas where step out drilling could quickly expand the mineralisation. This is most evident to the north where higher-grade mineralisation is open at relatively shallow depths and not drill tested below approximately 60 m from surface. Higher-grade silver mineralisation is also open to depth under the core of the deposit where interpreted “feeder structures” represent an attractive target for higher grade mineralisation
The Thomson Silver Spur MRE, as currently defined, is a modest size. However, the mineralisation remains under drilled with the high-grade silver – zinc mineralisation historically mined at the deposit, a priority drill target for Thomson. The Thomson block model highlights that mineralisation is to open depth requiring further drill testing to determine the full depth extent of the deposit.
Location and Geology
The Texas district is hosted by the early Permian age Silver Spur sedimentary basin. The Texas mineral district is developed over 50 sq. km area containing a diverse range of silver – gold, copper and base metal deposits styles including:
- Twin Hills is a sediment hosted, low-grade, silver-(gold) deposit with minor associated zinc, lead and copper. Approximately 25% of the known sulphide deposit was extracted via the previous Twin Hills open pit and heap leach operation, leaving silver – gold sulphide mineralisation outcropping in the pit floor, accessible for a potential restart of mining operations.
- Mt Gunyan is an undeveloped silver (gold-zinc-lead) deposit that outcrops as a prominent hill 3 km NE of the Twin Hills pit. Mt Gunyan comprises sediment hosted, low-grade, fracture vein related deposit. The majority of the deposit is strongly-to-partially oxidised with silver mineralisation starting from surface and continuing to depths of 150 m below surface and remains open below this depth.
- Silver Spur is a structurally controlled silver-base metal deposit located 2 km southeast of the Twin Hills open pit. Between 1892 and 1925 the Silver Spur underground mine produced approximately 2.19 Moz silver (average grade of 800 g/t Ag), and 690 t of zinc, 1,050 t of lead and 990 t of copper and by-product gold from approximately 100 kt of ore. The silver-zinc (lead–copper) halo and remnant high-grade silver mineralisation was not extracted by the historic mining operation. Thomson’s work has shown that the deposit has an unmined small oxide – transition zone overlying a larger primary sulphide zone of mineralisation.