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Synchysite-(Ce) Psm Petersenite-(Ce) With Donnayite Group

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LMB622807

Synchysite-(Ce) Psm Petersenite-(Ce) With Donnayite Group

Analysed
Pseudomorph

Description Tabs

Description
Locality: 
Poudrette Quarry, Mont Saint-Hilaire, Québec, Canada
Class: 
Combination
Size Range: 
Small miniature (3-4.5 cm)
Size: 
3.5 × 3.5 × 2 cm
Weight: 
25.00gr
Description

PSMs of synchysite-(Ce) after petersenite-(Ce) and/or rémondite-(Ce) were fairly abundant in parts of the Poudrette pegmatite, and some were quite large. Most of these consist of beige micaceous plates that make “swirly” patterns on the surface of the PSMs. The ones on this specimen are of a less common, pale greenish,  type  that is “pebbly” on the outside, but shows the same sort of platy interior. The prisms on this specimen have not been analyzed, but qualitative EDS for a similar specimen was consistent with synchysite-(Ce). When immersed in HCl, there was a prolonged period of effervescence with, from time to time, white, insoluble, flakes being thrown off. So  in this case, the PSMs aren't just synchysite-(Ce), but I don't know what the other component is. 

Some of the prisms have “terminations”, although the “pebbly” texture obscures most of them. Some of the prisms also have small rosettes of a donnayite group mineral. Qualitative EDS indicates intermediate donnayite-(Y)/mckelveyite-(Y) composition. See the “Analysis” tab. 

A 7 mm section of one the longest prisms is shown in the first pair of photos (FOV 7.0 x 4.3 mm). A small (0.4 mm) donnayite/mckelveyite  rosette can be seen at far left.

The next pair of photos (FOV 3.6 x 2.3 mm) is a close-up of the right hand side of the previous photos. Similar rosettes of donnayite/mckelveyite can be seen near center. This photo also shows the “pebbly” texture of the PSMs. Note that one of them has a fairly sharp “termination”.

A  larger (0.65 mm) donnayite-mckelveyite rosette is shown in the center of the next pair of photos (FOV 3.6 x 2.3 mm). The “pebbly” appearance of the PSMs is even more apparent. In the backround are small, but nice, olive colored, siderite rhombs.

The true color of the siderite is better represented in the full view photo. In that photo, the synchysite PSMs in the main cavity span about 1.5 cm.

Single item shipping weight (no case) is 3.6 oz (102 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 increases by about $0.20 per ounce. Above 13 oz, I will use Priority Mail (ca $9.25 including packing – varies by destination). 

Mineral Data
What's on the rock

Synchysite-(Ce)

Formula: 
Ca(Ce,La)(CO3)2F
Strunz: 
5.BD.20c
Hardness: 
4.5
Type Locality: 
Narsaarsuk pegmatite (Narssârssuk pegmatite), Narsaarsuk Plateau, Igaliku (Igaliko), Narsaq, Kujalleq, Greenland

Petersenite-(Ce)

Formula: 
Na4(Ce,La,Nd)2(CO3)5
Strunz: 
5.AD.15
Crystal System: 
Monoclinic
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
Analysis
Analysis Report - only: Synchysite-(Ce) Psm Petersenite-(Ce) With Donnayite Group
LMB minerals

Seller Information

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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.