Nimbus is a shallow-water and low-temperature VHMS deposit with epithermal characteristics (i.e. a hybrid bimodal felsic deposit), which is consistent with its position near the margin of the Kalgoorlie Terrane.

The local stratigraphy comprises a NW-trending and steeply dipping bimodal-felsic package of volcanic rocks (i.e. quartz-feldspar porphyritic dacite and lesser basalt, plus their autoclastic equivalents) with subordinate carbonaceous mudstone, tuff, polymict conglomerates and volcanic breccias. Komatiite flows, volcanic sandstones/siltstones, carbonaceous mudstone, basalt and dolerite were intersected in a distal drill hole (Hollis 2016).

Economic VHMS mineralisation in the Archaean Yilgarn Craton of Western Australia is largely restricted to two main zones of juvenile crust as revealed through regional (Nd, Pb) isotope variations. One of these zones runs north- south through the central Eastern Goldfields Superterrane and is associated with the high-grade Teutonic Bore, Jaguar and Bentley deposits, plus subeconomic VHMS mineralisation further south at Anaconda and Erayinia (Hollis 2016).

Mineralisation
Nimbus primary sulfide resources occur as a series of stacked plunging lenses, overlying mined supergene and oxide mineralisation.

In the primary sulfide zone, early well-developed massive pyrite is underlain by:
1. Semi-massive, stringer and breccia-type Ag-Zn±Pb(Cu-Au) sulfides (including: pyrite, lowand high-ir ........

It is assumed the project will be developed as an underground mining project, although mining studies are examining open pit opportunities.

Nimbus silver mine operated from 2003 to 2007, producing 3.6 million ounces of silver at an average grade of 352 g/t silver (11.7 oz/t).
• Nimbus Statistics (2007):
Tonnes Processed: 318,992 tonnes
Average Grade: 352 g/t silver
Production: 3.616 Million ounces of silver

Open pit surfaces for the Discovery Pit, East Pit (tails surface) and East Pit end of mining surface.

The tails were deposited in the East Pit, one of two open pits making up the Nimbus base metals project operated by Polymetals from 2003 to 2006.

- subscription is required.