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Improving Mindat.orgHellyerite

21st Jul 2009 17:18 UTCReiner Mielke Expert

According to the original AM (Vol.44) description of the species by Williams et al. 1959, Hellyerite is blue. In the data base are shown pictures of green Hellyerite? It is my understanding that Hellyerite is unstable and turns to green Zaratite or ?. Are the green crystals in fact pseudomorphs?

22nd Jul 2009 19:43 UTCKnut Edvard Larsen 🌟 Manager

The photos in question can be seen at http://www.mindat.org/gallery.php?min=1853

The color was indeed different, and the green suspiscious.

According to Anderson et al (2002), citing Henry and Birch (1992), hellyerite is relatively unstable and, if not kept in an air-tight environment, hellyerite decomposes in time to an uidentified poorly crystalline phase different from hellyerite.

Anderson, P., et al. (2002): Famous mineral localities: The Lord Brassey mine, Tasmania. Mineralogical Record. 33, 321-332.

Henry and Birch (1992) : http://www.minersoc.org/pages/Archive-MM/Volume_56/56-383-252.pdf

Williams et al (1959): http://www.minsocam.org/ammin/AM44/AM44_533.pdf

22nd Jul 2009 20:33 UTCUwe Kolitsch Manager

I once checked transparent green "crystals" of hellyerite from this mine by SXRD.

They turned out to be +/- amorphous (due to dehydration?).

23rd Jul 2009 10:14 UTCAndrew Tuma Expert

I have collected at the Lord Brassey mine a number of times since the mid 1990's. Over this time I have collected Hellyerite from both the dumps and underground. In this time all the lovely blue has changed to a soft green on each specimen, the colour exactly represent the two colours as described by Reiner - no matter if from above or underground sources.

To try to beat the problem, I have stored some in airtight containers, in sealed containers with water, a couple were stored in the fridge (much to the exasperation of the fridge owner) and some in normal air and humidity...it does not matter, they have all turned from blue to green when opened up or removed from the mine. I would be surprised this changed mineral is Zaratite as zaratite does form with hellyerite insitu as a secondary mineral after Heazelwoodite.

The last time I collected at Lord Brassey Mine, I found no hellyerite on the dumps, interestingly this was after a very dry summer and winter, so dehydration has likely affects as Uwe stated.

I know a few local dealers that refuse to sell hellyerite due to the instability of the mineral. From this I would expect that the providers of the green hellerite photos on Mindat had purchased blue hellerite that changed to green and still feel they have what they purchased originally.

This problem is not uncommon, how many the specimens in our collections have undergone slight changes???

Reiner, I hope this assists, and likely supports your comments but until the amorphous material is classified what can be done???

Andrew Tuma

23rd Jul 2009 13:05 UTCSteve Sorrell Expert

Mine are still blue and have not altered. Most specimens are housed in plastic micro boxes. I have sent specimens to other collectors in many parts of the world and they all turn green. Interestingly, Andrew only lives about 250k from me, and closer to the mine!

Ralph Bottrill in the new Catalogue of the Minerals of Tasmania states that 'hellyerite is relatively unstable and, if not kept in cool air-tight environment, decomposes to powdery, amorphous, zaratite-like phases, plus otwayite and other minerals".

I have found a few 'pseudomorphs' (crystal habit of hellyerite, but pale green and opaque) but only rarely. The blue crystalline hellyerite is found generally in 'sealed' zaratite. On the dumps, you look for veins of zaratite in serpentine, and use a screwdriver to 'twist' it open, and if lucky, have hellyerite inside.

Regards

Steve

23rd Jul 2009 14:27 UTCReiner Mielke Expert

Has anyone tried dipping them in clear laquer? So strickly speaking the green crystal photos are labeled incorrectly and should be labeled as pseudomorphs of hellyerite. Also it would be nice to have this instability mentioned in the database somewhere.

23rd Jul 2009 14:50 UTCRalph S Bottrill 🌟 Manager

I agree with Andrew, I have not found any hellyerite on the dumps there in the last few years - perhaps its too warm lately? Little or nothing in the adit either. A winter visit may be called for, but is difficult. I have had some samples last for a year or two when kept cold and wet, but they eventually dehydrate(?) to an amorphous (NOT poorly crystalline) zaratite-like phase - as we reported in Andersen et al. The classic zaratite is a darker green and vaguely botryoidal, but the veinlets and nodules commonly have a core of hellyerite suggesting most may have formed this way and the colour may vary with time. I do need to do more work with zaratite, but its rather variable in composition and only rarely shows some (poorly) crystalline components, so its not easy.

23rd Jul 2009 16:19 UTCLeon Hupperichs Expert

Made some comments to my pictures of Hellyerite.

23rd Jul 2009 16:21 UTCMarco E. Ciriotti Manager

Hi all,

knowing the possible instability (dehydration?), I have treated my specimen with abundant hairspray and stocked in plastic box. The few crystals remained blue...

24th Jul 2009 01:02 UTCRalph S Bottrill 🌟 Manager

Marco

Good idea, I may take hairspay on my next trip!

24th Jul 2009 08:30 UTCElmar Lackner Expert

Thank's for this informations, I have updated my picture descriptions :-)

24th Jul 2009 09:47 UTCAndrew Tuma Expert

Hey Ralph,

Great idea - I'll bring a blowdryer and maybe Steve can toss in a pair scissors and we can all go somewhere "hair-raising" for our next trip....its been a while.(:D

24th Jul 2009 13:10 UTCSteve Sorrell Expert

Only if I can get myself an electric zimmer frame Andrew!

24th Jul 2009 13:16 UTCRalph S Bottrill 🌟 Manager

I look forward to it Andrew, but you know I like to let my hair down when out bush!

25th Jul 2009 19:24 UTCUwe Kolitsch Manager

The original publication (http://www.minsocam.org/ammin/AM44/AM44_533.pdf) doesn't mention dehydration/alteration of their natural material (massive, with "rare crystal fragments"), but of synthesised material. However, heating the type material at 50°C for 1 week turned it into the alteration phase.

26th Jul 2009 13:56 UTCSteve Sorrell Expert

Maybe there are some "hot rocks" up at Lord Brassey!

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