Mildura gemstones and minerals

[Ark]

Hello everyone, I've recently become interested in prospecting and was wondering if you can find any gemstones or minerals in Mildura

 

[user 4386]

I have not heard of any myself, and would not think it a favourable area geologically for gems (if present, they would probably be forms of silica like chalcedony)

 

[Theduke]

Theres been Zircon hits south of there, best bet is try doing some local research ie library for old articles and see what you can find

 

[user 4386]

Theres been Zircon hits south of there, best bet is try doing some local research ie library for old articles and see what you can find

Where? I would have thought that very unlikely close to Mildura, given the complete absence of volcanic or intrusive rocks in the area.

 

[Theduke]

Herere the map of the area. Living in the NT its just down the road but not sure what anyone else would call it :lol: theres only Gypsum from what I have on my map for the immediate area around Mildura

 

[user 4386]

Yes - lots and lots of gypsum - but not gemstones to my knowledge. The gypsum is associated with salt pans and has been mined for plaster board I think (eg Raak Lakes). i.e. with a hardness of 2, gypsum is never a gemstone.

Geology is a pretty good guide to presence or absence of gemstones.

 

[Lefty]

Unfortunately, the area doesn't look very promising for gemstones from my understanding https://macrostrat.org/map-raster/#11/-34.1476/-217.8781

It appears to be all sedimentary-type stuff or at least nothing that resembles volcanics. No intrusives such as granite.

The area to the west and north-west looks more interesting but it could be quite some distance - the area around Mildura looks to be the wrong geology for gemstones for hundreds of km in all directions, unfortunately.

I believe there's been some nice quartz crystal specimens found somewhere out the back of Adelaide, though from memory when we used to visit the in-laws near Whyalla, Mildura to Adelaide is a fair hike.

 

[user 4386]

Unfortunately, the area doesn't look very promising for gemstones from my understanding https://macrostrat.org/map-raster/#11/-34.1476/-217.8781

It appears to be all sedimentary-type stuff or at least nothing that resembles volcanics. No intrusives such as granite.

The area to the west and north-west looks more interesting but it could be quite some distance - the area around Mildura looks to be the wrong geology for gemstones for hundreds of km in all directions, unfortunately.

I believe there's been some nice quartz crystal specimens found somewhere out the back of Adelaide, though from memory when we used to visit the in-laws near Whyalla, Mildura to Adelaide is a fair hike.

Agreed - you would probably be best going north into the Broken Hill region where there is a wide range of gemstones because of all the granites and crystalline rocks (beryl, garnets, tourmaline to name but a few).

 

[user 4386]

Unfortunately, the area doesn't look very promising for gemstones from my understanding https://macrostrat.org/map-raster/#11/-34.1476/-217.8781

It appears to be all sedimentary-type stuff or at least nothing that resembles volcanics. No intrusives such as granite.

The area to the west and north-west looks more interesting but it could be quite some distance - the area around Mildura looks to be the wrong geology for gemstones for hundreds of km in all directions, unfortunately.

I believe there's been some nice quartz crystal specimens found somewhere out the back of Adelaide, though from memory when we used to visit the in-laws near Whyalla, Mildura to Adelaide is a fair hike.

Agreed - you would probably be best going north into the Broken Hill region where there is a wide range of gemstones because of all the granites and crystalline rocks (beryl, garnets, tourmaline to name but a few). Less then 200 km of fast desert driving would get you into very promising rocks.

 

[Lefty]

Yes, the area up toward Broken Hill caught my attention...

Broken Hill Group
Age: Paleoproterozoic (2500 - 1600 Ma)
Stratigraphic name: Broken Hill Group

Description: Metasediments, garnetiferous quartzo-feldspathic gneiss, amphibolite, minor garnet and gahnite-rich rocks, banded iron formation

Comments: high grade metamorphic rock; synthesis of multiple published descriptions

Lithology: high grade metamorphic rock

https://macrostrat.org/map-raster/#8/-31.938/-215.491

We also used to go through Broken Hill from central QLD to SA sometimes - I recall that the mining museum in Broken Hill had an awesome mineral display!

 

[user 4386]

Yes, the area up toward Broken Hill caught my attention...

Broken Hill Group
Age: Paleoproterozoic (2500 - 1600 Ma)
Stratigraphic name: Broken Hill Group

Description: Metasediments, garnetiferous quartzo-feldspathic gneiss, amphibolite, minor garnet and gahnite-rich rocks, banded iron formation

Comments: high grade metamorphic rock; synthesis of multiple published descriptions

Lithology: high grade metamorphic rock

https://macrostrat.org/map-raster/#8/-31.938/-215.491

We also used to go through Broken Hill from central QLD to SA sometimes - I recall that the mining museum in Broken Hill had an awesome mineral display!

There is even a beryl street (a mine there provided the beryllium for the first space race from a mine in pegmatite).

Much of New South Wales industrial beryl production has been from pegmatites in the Broken Hill area. The main mines were at Egebek, where the Triple Chance, Lady Beryl and Spar Ridge mines were the largest producers. Other beryl localities occur around Broken Hill and in the Euriowie area where an unusual caesium-bearing beryl has been reported (Rayner 1960).

The garnets are awesome:

https://youtu.be/0iSh_kBkT2Y

The green spinel gahnite is everywhere - some is large and attractive and I wonder if anyone has tried cutting it from there:

http://www.gemstones-guide.com/Gahnite.html

Tourmaline is widespread:

https://www.smedg.org.au/Coianiz Torrey Broken Hill Pegmatites.pdf

https://pubs.geoscienceworld.org/se...gin-and-significance-of-tourmaline-rich-rocks

For example, elbaite is recorded with beryl at the Trident mine, Byjerkerno Creek.

"Australian Turquoise are rare, blue gemstones with beautiful coffee and chocolate egg-shell and spider web patterns from Broken Hill in the Australian state of New South Wales".

Some Broken Hill rhodonite could possibly be cut:

https://i.pinimg.com/736x/64/8c/35/648c357a07e948e54064de01b82002a9--south-wales-crystal-healing.jpg

Apparently they are:

https://www.gia.edu/doc/Inclusions-in-Transparent-Gem-Rhodonite.pdf

Ian Plimer wrote a book on mineral collecting localities of Broken Hill, now out of print:

https://catalogue.nla.gov.au/Record/2786379

 

[Lefty]

Oh man, what a shame the in-laws left SA so we no longer make forays down through Broken Hill - gem and mineral specimen heaven!!!

Ark - get thee to Broken Hill whenever you have a long weekend!!!

 

[user 4386]

Many properties will let you on, but they are dead set against people who enter without permission. Some might want public liability insurance

 

[Ark]

Cheers for all the information everyone, broken hill is only 3 hours away so it sounds like a perfect get away for a few days when I have some time off