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Donnayite-(Y) Pyrite & Fluorite With Donnayite Group


Donnayite-(Y) Pyrite & Fluorite With Donnayite Group

Strangely Fluorescent

Description Tabs

Poudrette Quarry, Mont Saint-Hilaire, Québec, Canada
Mixed Specimens
Size Range: 
Thumbnail (1-3cm)
1.5 × 2.5 × 1.7 cm
Largest Crystal: 

This is a lot consisting of two very different specimens of “donnayite”. They are both from analyzed finds (see the “Analysis” tab).

It is impossible to visually distinguish donnayite-(Y), mckelveyite-(Y) and ewaldite at MSH. It can be impossible even with EDS because the species are often intergrown with each other and with synchysite-(Ce). (In addition, there are some “UK” members of this group.) For one of the specimens, donnayite-(Y) partly replaced by or mixed with FeSO4 and pyrite, is a likely enough ID, so that the label will reflect that. (The dimensions given are for this specimen.)

For the other specimen (which is 2 x 3 x 2 cm in size), XRD (on another sample) said "donnayite group", and a quick and dirty EDS scan confirms donnayite-(Y) with significant Ba. (See the "Analysis" tab.) This specimen is actually the more interesting of the two, because the “donnayite” fluoresces – something that has not been “officially” reported for any member of the group. The yellowish fluorescence isn’t very bright – but it’s clearly there. (But this isn't a fluoresecent dispaly piece by any means!)

The first pair of photos shows the better of the two “donnayite” crystals (or aggregates) on this specimen. It looks like a small (1.7 mm), yellow, pine cone. The next photo shows this entire specimen. The matrix is microcline and analcime sprinkled with natrolite/gonnardite. (I’m not sure what the lustrous brownish cystal is that  the “donnayite” is attached to. Maybe just calcite.)

The second specimen (1.5 x 2.5 z 1.7 cm) features blue-gray donnayite-(Y) with Fe and S - perhaps as FeSO4 . (See the “Analysis” tab.) It is typical at MSH for donnayite to be sprinkled with and to include pyrite. It isn't clear just from EDS whether any or all of the Fe and S is coming from such pyrite, or if (at least some of) the pyrite has altered to an FeSO4 mineral. There is certainly plenty of pyrite left that could have been mixed in. There are also tiny purple fluorite cubes (some zoned) on dolomite. The next three photos are for this specimen.

FOV in the first close-up is 6.0 x 3.8 mm. The longest “donnayite” is 1 1/4 mm. FOV in the second close-up is 5.8 x 4.1 mm. The third photo is a full-view showing also associated dolomite and smoky quartz. Found 6/97 in a hornfels seam near the famous Poudrette pegmatite.

Combined shipping weight 3.3 oz. Outside the USA, the stated postage and packing rate applies up to a total weight of 8 oz (225 g).

Within the USA, postage for total weights up to 13 oz ranges from $4.25 to $6.50 (including packing etc) regardless of destination. Above 13 oz, I will use “own box” Priority Mail. The rate, including packing, varies by destination from $7.25 to $9.50.

See my updated “Shipping Policy” for details

Mineral Data
What's on the rock


Type Locality: 
Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada


Crystal System: 
6.0 - 6.5


Crystal System: 
Type Locality: 
Jáchymov (St Joachimsthal), Jáchymov District (St Joachimsthal), Krušné Hory Mts (Erzgebirge), Karlovy Vary Region, Bohemia (Böhmen; Boehmen), Czech Republic
Analysis Report - only: Donnayite-(Y) Pyrite & Fluorite With Donnayite Group
Analysis Report - only: Donnayite-(Y) Pyrite & Fluorite With Donnayite Group
Analysis Report - only: Donnayite-(Y) Pyrite & Fluorite With Donnayite Group
LMB minerals

Seller Information

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Seller's terms and conditions

In addition to the standard terms and conditions, please note the following. Almost all IDs are visual. While in most cases the ID is obvious, there may be cases where it is not. If you are doubtful about a particular ID, please ask for more information. Or do not bid! Similarly, if you are not sure that the specimen meets your criteria, do not bid. I have tdone the best I can with the photos. Nevertheless, if you are not happy with a specimen for any reason, I will refund the bid price – but not the shipping costs (unless the fault is clearly mine) – if the specimen is returned. This policy applies even if analysis of the specimen shows that my ID was incorrect. When in doubt, ask - or don’t bid. Note that most crystals at MSH and Varennes are micros - even if on large specimens. Please pay attention to the stated sizes. Any customs duties, fees etc. are the responsibility of the buyer.

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