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Prehnite : Ca2Al2Si3O10(OH)2

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Copyright © Collection and Copyright © 2022, Paul De Bondt
 
 
 
 
minID: R41-WMF

Prehnite : Ca2Al2Si3O10(OH)2

Copyright © Collection and Copyright © 2022, Paul De Bondt  - This image is copyrighted. Unauthorized reproduction prohibited.
Dimensions: 165 mm

A superb old time prehnite specimen from this now forbidden-to-collect locality.
It comes with an old Deyrolle, Rue du Bac, Paris, label.
Purchased from Clavel Minéraux at the 2022 Ste Marie show. Ex Thibault collection.
Collection and photo, Paul De Bondt.

This Photo was Mindat.org Photo of the Day - 24th Aug 2022

This photo has been shown 1146 times
Photo added:26th Jun 2022
Dimensions:3543x2326px (8.24 megapixels)

Data Identifiers

Mindat Photo ID:1227468 📋 (quote this with any query about this photo)
Long-form Identifier:mindat:1:4:1227468:7 📋
GUID:a227c527-ca1c-425a-971b-968aa9490a80 📋
Specimen MinIDR41-WMF (note: this is not unique to this photo, it is unique to the specimen)

Discuss this Photo

PhotosShow us your favorite prehnites

28th Jun 2022 14:51 UTCPaul De Bondt Manager

I'm surfing on the wave created by Kevin to launch a new topic.
You probably know I am a real sucker for prehnites and after looking since 1980 for a good prehnite from La Combe de la Selle, it seems that my patience was rewarded at the 2022 Ste Marie show.
Show us YOUR favorite prehnites and especially if you have some hidden treasure.

Zenjoy and keep safe.
 

28th Jun 2022 15:26 UTCJcrockett

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I'm more about the calcite on this but it's quite a good prehnite example from Fischbach in Germany. There's some interesting crystallization around the spots where there's bitumen.

28th Jun 2022 15:32 UTCRolf Luetcke Expert

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One from Charchelejo Jaen, Spain, 3x3cm.

28th Jun 2022 15:34 UTCRolf Luetcke Expert

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Paterson New Jersey piece, 5x4cm.

28th Jun 2022 15:36 UTCRolf Luetcke Expert

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One from Loudoun Co. Virginia, 32x22mm.

28th Jun 2022 16:22 UTCErik Vercammen Expert

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Crystals of 1 cm on greenstone, found near Goppenstein, LÖtschental, Wallis, Switzerland.

28th Jun 2022 17:22 UTCHarold Moritz 🌟 Expert

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Looks like a green version of the famous hemimorphite "maggot ore" from Ogdensburg, NJ!

28th Jun 2022 17:23 UTCHarold Moritz 🌟 Expert

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Mushroom!

28th Jun 2022 17:23 UTCHarold Moritz 🌟 Expert

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Uncommon pastel blue.

28th Jun 2022 17:24 UTCHarold Moritz 🌟 Expert

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Whodathunkit!

28th Jun 2022 17:28 UTCHarold Moritz 🌟 Expert

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Breaking wave.

28th Jun 2022 17:38 UTCHarold Moritz 🌟 Expert

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Blue kisses!

28th Jun 2022 17:53 UTCtiny minerals

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Manassas Qy, Virginia - prehnite and byssolite on calcite on prehnite.  FOV 1 mm.

28th Jun 2022 18:07 UTCHerwig Pelckmans

Holy Cowlesite !!

Can you elaborate your explanation a bit, Tiny?
What crystal grew when and on what?
Crazy stuff!
Cheers, Herwig

28th Jun 2022 18:22 UTCtiny minerals

Base is prehnite, calcite next, then prehnites and a needle of byssolite on top of that.  It's all micros other than the base prehnite, so IDs could be off of course.

28th Jun 2022 18:25 UTCtiny minerals

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Not the best pic but here's a cluster on byssolite.  Same FOV - about 1 mm.

28th Jun 2022 18:54 UTCJolyon Ralph Founder

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Back in 1995 I went with my local club, the Sussex Mineral and Lapidary Society for a collecting trip in Scotland, and we ended up at the Loanhead Quarry which was at that time being actively worked.   A very nice quarryman met us and had a box of nice prehnite specimens for everyone - well almost. He had somehow miscounted and was two short for our group, and I was one of the two who missed out.  He felt bad about this and offered to later drive the two of us to his allotment where in his shed he had more prehnite pieces and would find some for us both.

We went to his shed and there was a barrel of nice pieces, a lot of it was clearly destined for lapidary rather than collecting, but both of us found nice pieces there.   But then I saw this piece, on the desk in his shed, and asked him about it.

15cm tall.

"Oh, sorry, that's a great piece and it's going to be expensive."

Ok... I asked... How much?

"Ten pounds!" he said proudly.

"I'll take it!" I said.   I added a couple of natrolite/analcime specimens to the pile and gave him £20 which he was delighted with.  But probably not as delighted as me!

29th Jun 2022 05:23 UTCTom Goodland

Loanhead Quarry is still being worked, but they are now very strict about not letting collectors in.

28th Jun 2022 18:55 UTCJolyon Ralph Founder

Random trivia: Prehnite was the first mineral named for a person

28th Jun 2022 19:15 UTCRobert Nowakowski

That is a cool piece of trivia

28th Jun 2022 22:01 UTCGabriel Plattes

Sage and co., and Werner and co., ended up nearly 'throwing hands' over that one! 'Plants were named after folk, see Linnaeus & co.', responded Werner (paraphrased), 'so why not minerals'? Witherite was an early nod also, also by Werner.
[Herwig was writing a little piece on this... What's taking, mate? ;) ]

28th Jun 2022 19:04 UTCHarold (Hal) Prior Expert

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28th Jun 2022 21:14 UTCKevin Conroy Manager

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A 10.3 cm wide prehnite after laumontite from Malad Quarry, Malad, Mumbai Suburban district, Maharashtra, India.

28th Jun 2022 23:40 UTCMark Heintzelman 🌟 Expert

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Here's a fairly rare Pennsylvania cockscomb Prehnite with from a limited find in the late 1930's made by D.M. Fraser and R.D. Butler at the basalt quarry near Cooperburg, Lehigh County.   Ex. J. A. Grenzig collection.  2 x 2.5 inch 

28th Jun 2022 23:48 UTCMark Heintzelman 🌟 Expert

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Here is probably my most showy prehnite specimen, an older and very gemmy mint green prehnite with minor white calcite from Passaic County New Jersey, most likely from the prospect park quarry. aprox. 18  x 18 x 5 cm 

29th Jun 2022 00:03 UTCMark Heintzelman 🌟 Expert

04273560017055627136106.jpg

The Prospect Park is also well known for these "blue" prehnite, fairly nicely translucent Prehnite crystallization on a bed of pumpellyite. aprox. 13 x 11.5 x 9 cm

29th Jun 2022 01:50 UTCTroy Schmidt

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This is one I picked up earlier this year from the O & G Woodbury Traprock Quarry, Connecticut, USA 

29th Jun 2022 02:07 UTCHarold (Hal) Prior Expert

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Kaiserslautern District, Rhineland-Palatinate, GermanyDimensions: 7 cm x 5 cm x 2.5 cm

Superb Prehnite from a unique locale. Acquired from Jewel Tunnel Imports -Formerly in John R. Ydren Collection.  

29th Jun 2022 02:14 UTCHarold (Hal) Prior Expert

05767590017055627139013.jpg
Koedoekop, Keetmanshoop Rural Constituency, ǁKaras Region, NamibiaDimensions: 5.8 cm x 3.4 cm x 2.8 cm.  One of my favorite Prehnites  

29th Jun 2022 06:17 UTCOlav Revheim Manager

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This is one of my favourite prehnites. Self collected some 20 years ago. 

Olav

29th Jun 2022 06:40 UTCVolker Betz 🌟 Expert

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One from the Rauschermühle.
Volker

29th Jun 2022 08:52 UTCGabriel Plattes

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Prospect Quarry, New South Wales, Aus.

29th Jun 2022 09:36 UTCRui Nunes 🌟 Expert

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And a differente one from Montijos quarry, Portugal (fov ~ 55 mm).

29th Jun 2022 11:57 UTCKeith Compton 🌟 Manager

Gabriel
That's pretty darn good for Prospect NSW - could you please upload that to the Prospect gallery?

Cheers

29th Jun 2022 22:28 UTCGabriel Plattes

Dear Keith,

I would not know how to go about that, but you may use the image for that purpose (should you wish). It is from a 'private collection' (ie. currently), & ex George Stacey.

Yours faithfully, Gabriel.

30th Jun 2022 09:20 UTCOlav Revheim Manager

Keith Compton 🌟 Manager  ✉️

That's pretty darn good for Prospect NSW - could you please upload that to the Prospect gallery?
 I guess the FOV must be wrong? Unless the person holding the specimen has a 2 cm wrist?

Olav

9th Jul 2022 09:51 UTCColin Merriman

Nice!! These specimens are very hard to come by from this location. I love Prehnite from Prospect NSW.

29th Jun 2022 09:56 UTCPaul De Bondt Manager

09499890017059260081096.jpg
Thnk you all for you nice pics and specimens.
Here's another La Combe de la Selle.
Top helmet 32mm.

Zenjoy.

29th Jun 2022 12:06 UTCBruce Cairncross Expert

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Here's an orange prehnite from N'Chwaning II mine in the Kalahari manganese field. Field of view 3 cm.

30th Jun 2022 18:23 UTCRolf Luetcke Expert

Bruce,
Now that is one very nice piece, love the color.

29th Jun 2022 12:40 UTCJyrki Autio Expert

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From Vagberget Quarry, Southern Finland.

29th Jun 2022 12:42 UTCJyrki Autio Expert

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And other from Polvenniitty Quarry, Southern Finland.

29th Jun 2022 12:46 UTCLarry Maltby Expert

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This is a slab of Prehnite with copper inclusions and some Keweenaw Pegmatite at the top. Collected at the Clark Mine, Keweenaw Co. Michigan.

 

29th Jun 2022 12:59 UTCLarry Maltby Expert

08217660017055627139269.jpg

This is banded Prehnite from the North Kearsarge No. 3 Mine, Keweenaw Co. Michigan. The voids were all filled with calcite. This is the result of removing the calcite with acid.

 

29th Jun 2022 14:23 UTCMark Heintzelman 🌟 Expert

05832210017059260108908.jpg

Several unusual forms of Prehnite from South Eastern Pennsylvania.  From the Keystone Traprock Quarry associated with byssolite and Alpine cleft mineralization, and from the argillite with diabase intrusions occurrences at the Sillver Hill and Rock Hill quarries.

29th Jun 2022 15:02 UTCHarold (Hal) Prior Expert

08605830016016205901966.jpg
Watchung, Somerset Co., New JerseyDimensions: 13.0 cm x 7.5 cm x 4.5 cm. Label indicates pseudo after Glauberite.  

29th Jun 2022 15:05 UTCHarold (Hal) Prior Expert

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Bull Run Quarry, Conklin, Loudoun Co., VirginiaDimensions: 8.5 cm x 7.2 cm x 2.2 cm  

29th Jun 2022 16:20 UTCMark Heintzelman 🌟 Expert

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Several samples of Prehnite and other mineralization with deep green coloration due to the inclusions of chlorite/byssolite.  A characteristic well noted from the workings of the old Luck Quarry (Fairfax Quarry) at Centreville in Fairfax County Virginia.

29th Jun 2022 18:39 UTCHarold (Hal) Prior Expert

09595990017055627143603.jpg
 Prehnite with Quartz and Pyrite - Kostanay District, Kostanay Region, KazakhstanDimensions: 4.5 cm x 3.7 cm x 2.1 cm. Acquired at Denver show 2001  

30th Jun 2022 06:03 UTCBrian Fussell

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The only Prehnite I have found, Its likely a glacial deposit.  Ozaukee County, Wisconsin, Lake Michigan shoreline.

30th Jun 2022 09:22 UTCGabriel Plattes

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5.5 cm.
Part of an early twentieth century set (very likely by Ward's Natural Science Establishment, Inc.); ex Clifford G. Shultz, New Jersey.

1st Jul 2022 00:08 UTCMark Heintzelman 🌟 Expert

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Here's another old prehnite with an original Ward & Howell label noting the prehnite, which was far less common at Bergen Hill than it's associated pectolite.  However, this specimen pre-dates the identification of what it actually is . . . Stevensite from it's TL!

30th Jun 2022 16:45 UTCEd Clopton 🌟 Expert

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Its wide variety of habits and pleasant color make prehnite one of my favorite minerals.  Thanks for starting this thread!

Here is perhaps my overall favorite prehnite specimen, delicate fans comprised of thin blades of pale green prehnite standing on a calcite-covered vug surface 5.5 cm wide from Millington, New Jersey, ex James Zigras.

30th Jun 2022 18:26 UTCRolf Luetcke Expert

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Another from the Bull Run Quarry, Virginia, 5x7cm piece.

30th Jun 2022 18:27 UTCRolf Luetcke Expert

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One from Hay Market Quarry, Virginia with calcite, 6x5cm.

30th Jun 2022 18:29 UTCRolf Luetcke Expert

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Kind of a big one from Centerville Virginia out in our yard for a photo.

30th Jun 2022 18:41 UTCHarold (Hal) Prior Expert

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Another unique locale - Cheshire Traprock Quarry, Cheshire, New Haven Co., ConnecticutDimensions: 6.3 cm x 5.2 cm x 4.6 cm. Acquired from John Betts Minerals  

30th Jun 2022 18:44 UTCHarold (Hal) Prior Expert

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Lane & Son traprock quarries, Westfield, Hampden Co., Massachusetts:  Dimensions: 3.8 cm x 2.9 cm x 2.2 cm  

30th Jun 2022 18:49 UTCHarold (Hal) Prior Expert

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30th Jun 2022 19:44 UTCKelly Nash 🌟 Expert

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Prehnite with quartz, Djebel Melh, Morocco, 6.2 cm.  

 

30th Jun 2022 19:50 UTCRolf Luetcke Expert

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One from India with laumontite and scolecite 10x12cm piece.

7th Jul 2022 23:46 UTCDouglas Bank 🌟

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I have a VERY similar specimen that was sold to me as gyrolite, but I subsequently decided that it is prehnite on quartz (not so sure about the quartz). It is from the Malad Quarry, Mumbai, India. 

30th Jun 2022 19:52 UTCRolf Luetcke Expert

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Prehnite on actinolite from the Haymarket Quarry Virginia, 4mm fov.

30th Jun 2022 20:32 UTCJeff Weissman Expert

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Another John A. Manley specimen, collected circa. 1890 from "West Paterson," most likely Upper New Street. I especially like how the prehnite crystals are accentuated by the contrasting lighter colored edges 

30th Jun 2022 20:33 UTCJeff Weissman Expert

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This one is from the Roncari Quarry in Connecticut, supposed to be epimorphs after anhydrite.

1st Jul 2022 17:40 UTCEd Clopton 🌟 Expert

I doubt they are epimorphs, but fans of solid prehnite.  If they were epimorphs, the crystals probably would stand perpendicular to all of the surfaces of the inner crystal, with terminations bristling outward in all directions.  Here we see apparently large parallel crystals arranged in fans with terminations only on the curved outer edges similar to those in the specimen I posted above from Millington, New Jersey. 

30th Jun 2022 20:34 UTCJeff Weissman Expert

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And finally, this one from Prospect Park has an especially intriguing surface structure

30th Jun 2022 21:09 UTCDemetrius Pohl Expert

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A nice miniature, bluish-green prehnite on almost black epidote and small, white stilbite lathes from Sougounikoura diggings, Diako, Commune Diakon,Bafoulabe Circle, Kayes Region, Mali 5x4x4cm. 

30th Jun 2022 21:21 UTCDemetrius Pohl Expert

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A great yellow green prehnite on dark olive-green epidote, Djouga diggings, Bendougou, Commune Diakon, Bafoulabe Circle, Kayes Region, Mali, 16x11x8cm - Jeff scovil photo

1st Jul 2022 17:53 UTCHarold (Hal) Prior Expert

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My favorite Prehnite because of the provenance and locale.  Route 1 road cut, Calais, Washington County, MaineDimensions: 9.1 cm x 7.0 cm x 7.5 cm

Great locale specimen with provenance! Collected in the 1960's by W. P. Hinckley, co-author of "Volume 2 Maine Mines and Minerals - Eastern ME". Classic find encountered during road construction of Smoky Quartz crystals with an overgrowth of translucent light green Prehnite.  

1st Jul 2022 21:48 UTCMark Heintzelman 🌟 Expert

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Have to agree with you on that one Hal!  While I do collect for Maine localities specifically, these blocky crystals on a matrix of Smoky Quartz and feldspar is pretty peculiar for the species and makes the prehnite specimens from this occurrence really special.

 (We seem to have acquired this material from the same source . . . if that was actually you, then thanks a million for this really desirable addition!)

2nd Jul 2022 02:57 UTCHarold (Hal) Prior Expert

Mark,
     I believe you acquired this one from me in March this year.  I hated to part with it - but at 85, can't keep all.  I acquired it at a small local show in Maine about 20 years ago during a visit. Glad to know it has good collector home!!  Look for a unique locale Missouri barite soon.  .........Hal P

1st Jul 2022 22:13 UTCDon Windeler

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An older piece from Prospect Park, New Jersey.

I enjoy prehnite as well -- just don't have a lot of mine photographed.  I really like the isolated balls on this one.

D.

4th Jul 2022 19:39 UTCAllan Blaske

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Here is one from Keystone Point at the tip of the Keweenaw.  Pink/green prehnite (variety "patricianite", colored by chlorite and tiny flecks of native copper to give it the pink color) in basalt matrix.  Looks a little like thomsonite, but much too hard.  Maximum dimension of amygdule is 1.6 cm.  

4th Jul 2022 20:59 UTCRobert Nowakowski

Before you add it as patricianite, are you sure its not natrolite.

4th Jul 2022 20:43 UTCHerwig Pelckmans

Dear Allan,
Could you please add the data to your photo, so that it will be displayed on the Mindat page about "patricianite" ...
Cheers, herwig

4th Jul 2022 23:34 UTCAllan Blaske

Herwig,

The data is included on the photos For two specimens I added to the prehnite page  earlier this year.  The two photos of patricianite from the Keweenaw are linked below.  They are on the prehnite page, but not sure how to link them to the patricianite page as well.



Robert,

I think it is too hard for natrolite, as a steel pick doesn’t scratch.  Also, natrolite isn’t very common in the Keweenaw, only at a few spots.  I have some clear needles from the St. Clair mine, and some red ones with analcime from Copper Falls.  

Best, Allan

5th Jul 2022 04:01 UTCHerwig Pelckmans

Thanks, Allan, they are on the "patricianite" page now.

Cheers, Herwig

7th Jul 2022 15:03 UTCDouglas Bank 🌟

00095300017055733637719.jpg
This is a thumbnail specimen of lavender fluorescing prehnite, pink orange fluorescing pectolite, green fluorescing willemite, and blue white fluorescing needles of thomsonite-Ca. Additionally, there is non fluorescing native lead and andradite garnet. This specimen came from the Franklin Mine in Franklin, NJ. This image took first place in the photo competition at the 2022 Tucson Show for the fluorescent micromineral category, and it appears (poorly) in Vol 97, Issue 4 of Rocks and Minerals. 

7th Jul 2022 15:06 UTCDouglas Bank 🌟

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Same specimen in white light - 1.3 x 1 x 0.7 cm

8th Jul 2022 03:24 UTCHerwig Pelckmans

Hi Doug,
I assume the photo of the luminescence was made using only short wave UV ?
In any case: an impressive luminescent specimen!
Cheers, Herwig

10th Jul 2022 14:25 UTCDouglas Bank 🌟

Herwig, yes, that image is all shortwave. I have a long wave image as well, and the prehnite kind of fluoresces a lighter blue white than the rest of the specimen, but it really isn't a long wave specimen. 

7th Jul 2022 22:29 UTCBill Dameron 🌟 Expert

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8th Jul 2022 00:16 UTCGabriel Plattes

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Cuteness.

8th Jul 2022 00:18 UTCGabriel Plattes

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Renfrewshire-candy.

8th Jul 2022 13:28 UTCAndré Heyninck

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Prehnite with quartz from Sweden. Grönsjöberget, Borlange , Dalarna. This is a self-found piece.

8th Jul 2022 16:20 UTCVolker Betz 🌟 Expert

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Prehinite with Epidote from Iceland.

8th Jul 2022 17:08 UTCPaul De Bondt Manager

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Thank you all for the nice pics and superb specimens.
Here's my contribution for the day.
Prehnite from Carchalejo, Spain.
Zenjoy and keep safe.

2nd Aug 2022 15:15 UTCDemetrius Pohl Expert

Lovely prehnite, Paul.

8th Jul 2022 19:24 UTCMatt Ciranni

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I bought this small (~4.5CM) piece as a kid in or around 1981, at a gift shop in Vacaville, California. It was identified as a "Prehnite Mold" and it was an intriguing little specimen, and most importantly, affordable to an 11 year old kid.  But now as an adult, I am still intrigued by it. It is obviously some kind of epimorph or pseudomorph of some kind; but I am not sure where it originated from, or what the original mineral was (Calcite? Gypsum? Scolecite?) that it formed around.  This is something maybe one of the experts can help with?  There is a piece from India shown above that is similar; maybe this is from the same area?

8th Jul 2022 19:49 UTCErik Vercammen Expert

10th Jul 2022 06:06 UTCMatt Ciranni

This is why I love this site so much... I was finally able to learn about a specimen I have owned for my entire adult life, but which has always been a bit of a mystery. Thanks!

13th Jul 2022 08:29 UTCKeith Compton 🌟 Manager

Matt
And most probably is Prehnite after Laumontite.


13th Jul 2022 13:16 UTCErik Vercammen Expert

It is prenite grown on laumontite, and the laumontite got dissolved away, leaving hollows in the prenite stick.

9th Jul 2022 08:13 UTCHerwig Pelckmans

Herwig Pelckmans Expert  ✉️

Hi Doug,
I assume the photo of the luminescence was made using only short wave UV ?
In any case: an impressive luminescent specimen!
Cheers, Herwig

Guess the question got lost since I replied immediately "under" your photos, and not at the end of the thread. So:

@ Doug: please see my question quoted above
@ Bill: nice specimens! is the cause of the blue color for the Merelani prehnite known?
@ Gabriel: always great to see some old-timers! Thanks mate!
@ André: nice specimen for being self collected! Gefeliciteerd!
@ Volker: certainly a specimen I would love to have in my collection. A crystallographers dream!
@ Paul: a beautiful specimen from a somewhat less usual locality, photographed "au point"!
=> certainly a worthy addition from the great guy who started this wonderful thread!

@ Matt: thanks for show and tell of your prehnite. Such specimens were indeed widely available in the eighties. And you mentioned something very important:

I sure hope dealers will think of the kids and budding collectors when they do shows. The way prices have evolved make it very hard for kids and youngsters to find affordable specimens. Of course there are always the microminerals, but those need a binocular, and that's at least a few hundred bucks for a starters version...

There used to be a dealer at the main Tucson show who had a whole table full of inexpensive macro specimens (and yes, some of them were pretty neat) with prices ranging from 1 to 5 dollars ... don't know if he's still around... if I remember correctly, he had light yellow colored labels.

Cheers, Herwig

10th Jul 2022 00:42 UTCBill Dameron 🌟 Expert

I have no idea why the prehnite is blue. It changes to a much more lilac color under a mixture of halogen and mixed LEDs, in my cases. Photo is with household LEDs. 

10th Jul 2022 14:28 UTCDouglas Bank 🌟

Herwig, I replied above, but only just now. Yes, that is a short wave image. 

In these long threads, it is sometimes hard to see that someone replied to your/my comment and asked a question. 

As for the macros, I think it is hard to find dollar specimens, especially since the box itself might cost that much. I have a number of old macros that we bought through very inexpensive silent auctions at my club (though the micromineral part of that club is now defunct). In fact, I have no idea how I got the prehnite specimen posted above, and assume it must have been for a dollar or two at one of those auctions!    On the other hand, at that club meeting and seemingly at most micro meetings, there is a pile of freebies from people who no longer want all the material. I have several large containers of all the freebies we have come across at meetings over the past 12+ years. 

2nd Aug 2022 09:48 UTCPaul De Bondt Manager

08717670017059260767034.jpg
Thank you all for sharing your beautiful pictures.
Time to swing-on the tread again.
A specimen from a very unusual locality, St Andreasberg, associated with stilbite.
Ex J.F. Lannoë collection obtained from Gilbert Gauthier.
Not the best pic I ever took, sorry.

Keep safe.

2nd Aug 2022 12:36 UTCPaul De Bondt Manager

09940590017059260771810.jpg
And another fine Combe de la Selle locality.
A nice butterfly.

Keep safe.

2nd Aug 2022 13:54 UTCHerwig Pelckmans

I just realized I did not add a photo yet to this great thread.
Among my favorites, is one of Larry Maltby's photos, subtitled: 
"prehnite worms with copper heads"

According to Larry, the "worms" were found in a banded prehnite amygdule that was leached in acid.
Cheers, Herwig

2nd Aug 2022 15:06 UTCLarry Maltby Expert

06564990016089495378272.jpg

Herwig,

Here is a typical banded prehnite from the North Kearsarge Mine, Kearsarge, Houghton Co., Michigan. The vesicle was filled with calcite including bands of calcite alternating with the bands of prehnite. The calcite was leached away with acid resulting in the voids seen here. I found several of these and the “worms” were found in one of them.

Larry,

 

2nd Aug 2022 15:11 UTCHerwig Pelckmans

Larry,
That is a most amazing view. It shows etching calcite can be very rewarding!

What acid did you use to remove the calcite? All other minerals seem to be "unharmed" by that acid ...
Cheers, Herwig

3rd Aug 2022 12:03 UTCLarry Maltby Expert

Herwig,

I leached this many years ago. It was probably diluted Muriatic Acid.

 

3rd Aug 2022 15:02 UTCNik Nikiforou

01426790017059260791628.jpg
From the 2013-4 find of Prehnite crystals at Prospect Park, NJ.




3rd Aug 2022 15:17 UTCBryan Davis

You sure about the location and date?  These look like fantastic examples from the 2011 find at Lower New Street Quarry.

16th Aug 2022 13:26 UTCNik Nikiforou

Yes, you are correct, these are from the 2011 Lower New Street find.  I have edited the gallery photos with the correct locality.  Thank you for pointing this out Bryan.

7th Sep 2022 15:21 UTCPaul De Bondt Manager

03005630017059260841145.jpg
Time to swing this tread on again with a nice "La Combe de la Selle" specimen.
From the 1992 find.

Keep safe.

7th Sep 2022 15:22 UTCPaul De Bondt Manager

09127220015334776806271.jpg
And a large Merelani Hills specimen.

Keep safe.
 
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