Prehnite

[Wwoofa]

Hi,
This month's "Gem of the Month" is .... Prehnite.

Feel free to add more info & pics. If anyone has any questions about Prehnite then this is a good place to post them.

You might like to change your "Gem of the Month" votes now that this one has been covered.

General Information:
Prehnite is a silicate of calcium and aluminium. It most oftens forms as stalactitic or botryoidal aggregates, with only just the crests of small crystals showing any faces, which are almost always curved or composite. Very rarely will it form distinct well individualized crystals.

Its colour usually varies from light green to yellow but it can also be colorless, blue or white. In April 2000, a rare orange Prehnite was discovered at the famous Kalahari Manganese Fields in South Africa. It is mostly translucent and rarely transparent.

Prehnite was first described in 1788 for an occurrence found in Eastern Cape Province, South Africa and was named after Colonel Hendrik Von Prehn, commander of the military forces of the Dutch colony at the Cape of Good Hope from 1768 to 1780.

Here are a few useful links that should cover all of the main information.

Wikipedia - http://en.wikipedia.org/wiki/Prehnite
Mindat - http://www.mindat.org/min-3277.html
Gemdat - http://www.gemdat.org/gem-3277.html
Minerals.Net - http://m.minerals.net/gemstone/prehnite_gemstone.aspx

Fossicking Locations:
Prehnite can be found in various locations in Australia. The most well-known location for collecting Prehnite is Wave Hill in NT. There is also very good Prehnite at Tambar Springs in NSW.

NT - Wave Hill
Wave Hill is located in north-west Northern Territory. Excellent Prehnite and other gemstones are found here. The area seems to be both a designated fossicking area and under a mining lease at the same time. The NT gov't site states it's OK to fossick as long as you have permission from the leaseholder. I suggest that you read the info on the following two websites and then do further enquiries before fossicking. If anyone has up-to-date info on access please let us know.

http://www.nt.gov.au/d/Minerals_Energy/Content/File/pdf/FA07.pdf
http://www.ourterritory.com/katherine_region/wave_hill_fossick_site_.htm

Here are some pics...
[smg id=276 type=preview align=center width=400 caption="Wave Hill Prehnite"]
[smg id=3122 type=preview align=center width=400 caption="Wave Hill Prehnite"]
[smg id=3319 type=preview align=center width=400 caption="Wave Hill Prehnite"]
 
NSW - Tambar Springs
Tambar Springs is located in northern NSW, east of Coonabarabran. There are a few fossicking locations in the area but they are all located on private property so you will need permission from the land-owner before fossicking. The Prehnite is often found in a "finger-like" formation. These locations are also very good places to find zeolites such as Stellerite and Heulandite. There is a world-class display of this material at Crystal Kingdom in Coonabarabran.

Here's a link to Crystal Kingdom...
http://www.crystalkingdom.com.au/

Here is a pic...
[smg id=7114 type=preview align=center width=400 caption="Tambar Springs Prehnite"]

NSW - Prospect Quarry
Prospect is a suburb in western Sydney. Quarrying of blue metal first commenced around the early 1820s and ceased operations around 2010. The quarry is being redeveloped for housing and light industry. The quarry is famous for its world class Prehnite. You can still get excellent examples collected many years ago at club shows. Apart from Prehnite, many other minerals were also found there including Calcite, Zeolites and Aragonite.

Further info can be found here ...
http://www.prospectheritagetrust.org.au/page26.html

Here's a pic...
[smg id=7115 type=preview align=center width=400 caption="Prospect Quarry Prehnite"]

[steveo]

Prehnite I faceted Fullerton sent me.


http://aussielapidaryforum.com/forum/index.php?action=media;sa=media;in=6506;preview



Edited by admin to show thumbnail.

[southerly]

very nice, prehnite is one of my favourites.

[wallie]

I have just returned from visiting Wave Hill. I got the required permission quite easily and was given a mud map to assist with finding stones.

There is ridiculous amounts of prehnite on the lease and I managed half a bucket or so as I didnt want to be greedy.

 I was able to find amethyst crystals and clusters, smoky quartz crystals and clusters, agates and some pretty jasper too. I hope to visit again in 2018 but it is a long way from anywhere. I believe there are other sites in the vicinity that have quality gems but the locals have their lips sealed. I'll be working on loosening a few.

[MakkyBrown]

Sounds like you had a great trip, Wave Hill is on the list to do one day.

[MALACHI]

Always nice to read when one has been on a better than ordinary fossicking trip.    Had a member at my club who pretty much said the same about Wave Hill. Like Makky Brown its on my list too.    Wallie , while you were there did hear anything on some blokes that caught out a couple of years ago taking Prehnite  out in a full trailer.    Just curious if proper justice caught up with them and its great to know that permission is still being given to enter the station.

Cheers 

[wallie]

While I was there I heard a story of a couple that were completing their 2nd trip for the year and had taken a trailer load out the 1st time and were filling a second. I didnt see them and I believe they were taking material outside the lease. It is a huge area to fossick in. The station owners, I believe, are concerned with what is being taken and the crew at the Top Springs Hotel are too.
 I got my permission from Gerry Pauley, the co-owner of the lease and he was more than helpful.

[wallie]

Visited again this year and found prehnite outside the mining lease. While I only got a small amount some of it has nice colour from a pale green to a vibrant yellow.
I might try and visit again next year.