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Donnayite Group

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LMB633513

Donnayite Group

Type Locality for Donnayite-(Y)
Analysed

Description Tabs

Description
Locality: 
Poudrette Quarry, Mont Saint-Hilaire, Québec, Canada
Class: 
Crystals on Matrix
Size Range: 
Thumbnail (1-3cm)
Size: 
2.7 × 2.2 × 2.4 cm
Largest Crystal: 
0.11cm
Weight: 
20.00gr
Description

According to the original label (which see), this is cordylite, found 1993. But qualitative EDS (see the “Analysis” tab), shows that the red caps are intermediate donnayite/mckelveyite-(Y). The Sr peak is slightly higher than the BA peak and, moreover, the equipment used is more sensitive to Ba than to Sr, so probably this is closer to donnayite-(Y) than to mckelveyite-(Y). But qualitative EDS scans can be misleading. Peak heights can be affected by factors other than relative sensitivity or abundance.  WDS ($$$) - and perhaps XRD - would be needed for a definitive ID. (MSH is the TL for donnayite-(Y).)

In any case, the color zoning is very interesting – unique in my experience. Possibly it is due to the presence of Fe and/or Th in the caps. The white sections were not analyzed. It is not uncommon to find ewaldite with donnayite caps at MSH, but other things are possible – including a chemistry similar to the caps but without the Fe or Th.

In the first pair of photos (FOV 1.15 x 0.9 mm) the crystal (0.6 mm) does look a lot like some cordylite (apart from the zoning).

Apart from the peculiar red cap, the crystal (1.15 mm) in the second pair of photos (FOV 1.3 x 1.7 mm) looks more like a fairly typical ewaldite + donnayite cap combination.

The third pair of photos (FOV 1.35 x 1.85 mm) is another view of the crystal shown in the first pair of photos. Also show is the cap of another, larger, crystal next to it. (The “root” of this  crystal is not visible.)

Single item shipping weight (no case) is 3.5 oz (99 g). 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
Analysis
Analysis Report - only: Donnayite Group
Labels
Label Images - only: Donnayite Group
LMB minerals

Seller Information

Payment options: offline, paypal_wpp, paypal_wps

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.