FMF - Friends of Minerals Forum, discussion and message board

[Roger Warin]

Hi list,
I present a very rare little jewel of Mt St Hilaire (Poudrette Quarry). It’s the twin of Serandite on (110).
I have not found a comparable picture on Internet.
Roger.

[Chris Rayburn]

Beautiful Roger! I've not seen one like this before.

[John S. White]

Same here. Great to see such a perfect twin.

[Roger Warin]

Hello Chris, John,
Thank you very much Chris, John.
I took over a new pic to show that it's a twin.
The two upper faces (001) and (001) are not in the same plane (not coplanar). An angle of about 8 ° is between these faces.
Roger.

[Roger Warin]

Hi,
Serandite is a rare mineral, group pyroxenoids. It’s a mineral of igneous rocks. It’s discovered in the nepheline syenite (without quartz) in Mt St Hilaire. This is the Mn term related to the pectolite (calcium pole of the solid solution).
The pinacoids {-102} and {-101} are not present in the crystal. I have given because they are common and may be responsible of striations.
Twinning: Around [010] composition plane {100}.
Less commonly this contact twin on {110}.
Roger.

[Michael Shaw]

Beautiful specimen Roger. I have never seen another like it.
Michael

[Roger Warin]

The Mineralogical Record put this twin on the cover of the July-August 1990 issue dedicated to the Mt St Hilaire.
Difference: specimen 12.5 cm.
Roger.

[Don Lum]

[Pete Richards]

I can't let Roger have all the fun.... Here's my much less professional photo of my example of this twin. I was remembering it as self-collected, but a look at my catalog says that is not the case - I bought it.

[Roger Warin]

Hi Pete,
I gladly share the fun. Michel Houssa had the good eye to choose this specimen. I see that your specimen is very similar.
I do not know the period of the find, but this date is 1973 or 1988, I think so.
I’m not a professionnal, just a keen amateur.
Roger.

[Roger Warin]

Many thanks Don,
It is difficult to reproduce the color of a mineral. Much depends on the lighting. My photo was taken in the light of a typical gray and dark day in the Belgian climate. Little light and a rather long exposure.
That said, is that this specimen is rather red, but it also has a color component "orange blossom" (couleur fleur d’oranger) as said Lacroix, who discovered the mineral on the island of Rouma, Los Archipel, French Guinea and described it (1931). J. M. Sérand was his guide.
Roger.

[Roger Warin]

Hi,
Serandite, Mt St Hilaire, Quebec. Equant crystal.
Equant and euhedral crystals are always aesthetically pleasing. They summarize the crystalline forms presented in textbooks. I added the drawing oriented as the photo.

PS: I have not identified the small crystals. This may be a second generation of Serandite. What do you think about?
Roger

[Pete Richards]

A lovely single crystal with great deep salmon color! Yes, I think the small crystals are another generation of serandite.

[Roger Warin]

Thank very much Pete.
I really appreciate your comments.
Indeed, if I'm not mistaken, you were the first crystallographer to study and establish the laws of the two twins of serandite.
Is it not so?
Roger.

[Pete Richards]