Alfredton, Ballarat, Victoria

Alfredton is a suburb on the western side of Ballarat. In June 2013, a new housing subdivision was under development on the western side of Learmonth Street. Excavation had unearthed quite a lot of fresh basalt which had been gathered in piles around the subdivision. It is likely that this basalt will be crushed for road surfacing. In early June, Toby Billing stopped off to inspect the basalt and found mineralisation. He and Steve Sorrell subsequently visited the site and found a number of mineral species in vesicles.

Featured image: The rock pile!

Most have so far only been identified visually, although a number have been id’d by Peter Elliot using SEM. There are a number that are yet to be identified/confirmed. The list of minerals has been updated/amended based on the feedback from Peter.

The basalt is no longer accessible.

Minerals recorded to date (visual identification only unless otherwise indicated):

Aegirine (SEM indicates green “aegirine” has much more Ca than Na so if it is a pyroxene it is probably hedenbergite), Albite var. Andesine (SEM indicates that the colourless/white platy crystals have about equal sodium and potassium so are likely albite-orthoclase or andesine-anorthoclase), apatite (SEM confirmed), Aragonite, Augite (SEM confirmed), Dolomite (SEM confirmed), Fayalite, Ilmenite (SEM confirmed ilmenite, not hematite), Magnesite (SEM confirmed dolomite but not magnesite), Opal (var. Opal-AN) also known as hyalite, and Tridymite.

Aragonite and hyalite opal
Mineralised boulder
Pile of basalt boulders
Hyalite opal on ilmentite
One week after collecting!
Hyalite opal
Ilmenite on augite
Zoned ilmenite