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Helvine

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LMB612968

Helvine

Extremely rare at MSH
Analysed

Description Tabs

Description
Locality: 
Poudrette Quarry, Mont Saint-Hilaire, Québec, Canada
Class: 
Crystals on Matrix
Size Range: 
Thumbnail (1-3cm)
Size: 
0.7 × 1.5 × 1.2 cm
Largest Crystal: 
0.12cm
Description

Helvine is an extremely rare mineral at MSH – much less common than its rare cousin genthelvite. This specimen features a partly exposed crystal 1.15 mm on edge. This crystal is shown in the first pair of photos (FOV 2.5 x 1.95 mm). There are other crystals on the specimen, but they appear to be completely embedded in a blob of quartz and probably impossible to extract.

When first exposed (in 1995) these crystals had a strong, deep red, SW UV response. However, at present, there is little if any discernible fluorescence. I don’t know if this is due to the exposure to atmosphere, but perhaps it explains why the Horváths (Lapis and Revista 2000) state that helvine has strong red SW response, whereas Mandarino and Anderson (Moneteregian Treasures) state that there is none. Either way, the UV response (or lack therof) appears to be a good way to distinguish helvine from genthelvite (which invariably has a strong green response) at MSH.

In any case, the helvine ID was further confirmed via qualitative EDS. While comparison of peak heights in such scans can be misleading, in this case the Mn peak is so much higher than the Zn peak, that, even though Mn is more readily detected than Zn, there can be little doubt that this material is Mn dominant – i.e. helvine. (See the “Analysis” tab.)

Single item shipping weight is 2.7 oz (77 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

Helvine

Formula: 
Mn2+4(Be3Si3O12)S
Strunz: 
9.FB.10
Crystal System: 
Isometric
Hardness: 
6.0 - 6.5
Streak: 
White
Type Locality: 
Friedefürst Mine, Breitenbrunn, Breitenbrunn District, Erzgebirge, Saxony, Germany
Analysis
Analysis Report - only: Helvine
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.