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Mckelveyite-(Y) & Donnayite-(Y) On Gmelinite-Na

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LMB587173

Mckelveyite-(Y) & Donnayite-(Y) On Gmelinite-Na

Analysed

Description Tabs

Description
Locality: 
Poudrette Quarry, Mont Saint-Hilaire, Québec, Canada
Class: 
Crystals on Matrix
Size Range: 
Thumbnail (1-3cm)
Size: 
0.8 × 1.5 × 0.4 cm
Weight: 
1.00gr
Description

This specimen is from an (EDS) analyzed find. (But is not the one that was analyzed.) The material from the find was quite variable in appearance, but two samples, chosen to be as different as possible, both produced very similar scans. The scan presented here (see “Analysis tab”) is for the sample that was most similar to the one on this specimen.

While peak heights in qualitative EDS scans can’t really be used to determine relative abundances of elements present, a reasonable interpretation would be that this specimen is an inter-growth of mckelveyite-(Y) and donnayite-(Y). Alternatively this could just be Sr rich mckelveyite or Ba rich donnayite-(Y). (Mckelveyite and donnayite form a series. While the Ba peak (mckelveyite) looks higher than the Sr peak, the equipment used is more sensitive to Ba.) Ewaldite is less likely, but can't be ruled out on the basis of this scan. 

In any case, it seems reasonable to conclude that at least mckelveyite is present. Whether there is also donnayite and/or synchysite is less certain. 

As shown in the first pair of photos (FOV 3.6 x 2.4 mm), the pale yellow mckelveyite/donnayite “discs” (<= 0.4 mm) sit on very nice colorless rosettes of gmelinite-Na (ca 2.1 mm). Under a scope, the gmelinite has a very attractive silvery-gray appearance.

The second pair of photos is a broader view (FOV 4.5 x 6.6 mm) showing more of the gmelinite rosetettes. The largest is 2.8 mm in diameter. The blocky white crystals are microcline.

Single item shipping weight (no case) is 2.7 oz (76g). For shipments outside the USA, up to a total weight < 8 oz (225g), this can be combined with items from this or other auctions for the same postage.

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

Mckelveyite-(Y)

Formula: 
NaCaBa3Y(CO3)6·3H2O
Strunz: 
5.CC.05
Hardness: 
3.5 - 4.0
Type Locality: 
Diamond Alkali Daco No. 3, Green River Formation, Sweetwater Co., Wyoming, USA

Donnayite-(Y)

Formula: 
NaCaSr3Y(CO3)6·3H2O
Strunz: 
5.CC.05
Hardness: 
3.0
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

Gmelinite-Na

Formula: 
(Na2,Ca)[Al2Si4O12]·6H2O
Strunz: 
9.GD.05
Crystal System: 
Hexagonal
Hardness: 
4.5
Type Locality: 
Nero Mt., San Pietro, Montecchio Maggiore, Vicenza Province, Veneto, Italy
Analysis
Analysis Report - only: Mckelveyite-(Y) & Donnayite-(Y) On Gmelinite-Na
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.