Geology of the Hatta Mines

Hatta

The Hatta deposit was discovered by Mawarid in 2000 as part of a regional reconnaissance exploration programme. Mineralisation occurs as a gently dipping lens of massive sulphide about 200 x 100 m in size at the contact between a lower pillow basalt unit and overlying massive basalt. The pillow basalts are considered to be the part of the Geotimes Unit, which comprises the lowermost unit of the volcanic succession.


The overlying massive basalts possibly belong to the Lasail Unit, though as yet there are no lithogeochemical data to confirm this. The massive sulphide consists of brecciated pyrite, chalcopyrite and minor sphalerite, with variable contents of primary and supergene chalcocite. The massive sulphide mound is underlain by a silica-rich stockwork feeder zone that locally contains significant chalcopyrite. The massive sulphides and higher grade stockwork comprised a resource of 1.2 Mt @ 3.5% Cu, which was mined out in early 2009.

Hatta Extended

The Hatta Extended deposit is a small, but high-grade copper resource consisting of two stacked massive sulphide lenses that occur at a similar stratigraphic position to the main Hatta deposit (link to figure). These lenses have measured resources of 0.13 Mt @ 5.2% and 0.02 Mt @ 9.9% Cu, with outcrops of gossan in the area representing the oxidised remnants of a third, upper sulphide lens. The high copper grades at Hatta Extended are due in part to the presence of chalcocite, which in places is the dominant copper mineral. Recent infill drilling has identified a central feeder zone beneath a thicker accumulation of massive sulphide, with mineralisation grading to sedimentary jasper at the margins of the deposit. This deposit thus appears to represent a small hydrothermal vent system distinct from that at the main Hatta deposit.

Hatta South

This deposit consists of a small massive sulphide mound up to 25 m thick with a measured resource of 0.30 Mt @ 3.1% Cu. Mineralisation extends up-dip to a small gossan at the surface and grades to sedimentary jasper along strike and down-dip. Mineralisation consists of pyrite and chalcopyrite with minor chalcocite and is intruded by a sub-vertical WNW-trending mafic dyke. A relatively restricted silica-rich stringer zone occurs in the central part of the deposit, which acted as a feeder to the sulphide mound.