Osterfield Clay Pit (Central Victoria)

Location:

25 km east of Bendigo, Victoria
Mining Licence at the corner of the Axedale-Toolleen Road and the Knowsley – Barnadown Road, near Axedale

Regional Geological setting:

Tertiary Murray Basin sediments overlying Ordovician meta-turbidites of the Castlemaine Formation.  Locally overlain by Quaternary basalts

Target Minerals:

Ball clay (primary), industrial sand deposits (secondary)

Mineralisation setting:

Torrumbarry Clays, part of the Upper Miocene Wunghnu Group which includes the coarser facies of the Calivil Sand.
The clays are deposited in a cut-off channel or bend in the palaeo- Campaspe River, with clays deposited on the outer bend, and point bar sands deposited on the inside of the bend.

Target size:

Medium to significant tonnage of ceramic grade ball clay

Exploration History:

Located by R. Osterfield in 1950s.  Initial resource defined in 1960s by open hole drilling:

White Clay                          800,000 tonnes
Coloured Clay                      2.5 M tonnes
Sand & Gravels                    3.8 M tonnes

Exploration Tools:

Surveying (of existing pit)
Gridding on 50m x 50m
Mapping of exposed sand and clay deposits
AirCore drilling 86 holes on 50 x 100m
SG determinations

Significant Outcomes:

Environment of deposition determined, and implications for further deposits
An earlier (“2G”) clay deposit located beneath existing resource with an Inferred Resource of 2.5 M tonnes
Sands of various size and quality to over 4 M cubic metres