FMF - Friends of Minerals Forum, discussion and message board

[Philippe Durand]

thank you Volkmar and Sante

No it is not self collected . I would love that it was.
But I am afraid that this location is really far over my lock in range :(
.

[Tobi]

Really wonderful Fibbia specimen, Philippe!

[Philippe Durand]

thank you Tobi :)

[Philippe Durand]

:)

[Jordi Fabre]

[Philippe Durand]

Thank you for correcting Jordi :)

But are you absolutely sure ?

It seems to me a bit strange, as the seller is, as you are a recognized specialist of Morocco, and he makes a lot of purchase trips here, and I do not see any reason for him to change from magnetite to hematite....

And can magnetite crystallize as hexagonal plates ?
On my specimen, under magnification, there are two layers of material: one as hexagonal shiny black plates, and then more grey anhedral material over the black plates, that yes could be magnetite.

Could we have magnetite over hematite, or any replacement ?

[Jordi Fabre]

[Bob Morgan]

Magnetite can have six sided faces that are dodecahedral faces bound on four sides by other dodecahedral faces and on two by octahedral faces. But stacked plates are really strange. Toward the top they resemble 'spearhead' marcasite twins, but the angle is different from marcasite twins. Is there some twinning involved?

The reticular looking magnetites are just as strange. Some appear to have rectangular faces which necessitates cube faces, which are quite rare for magnetite. Can particular faces be examined and their forms discerned? How about the angles of their change in direction?

Thanks for another mystery to keep our imaginations alive and life interesting.

[Bob Morgan]

On second look the platy crystals toward the top of the photo are in parallel or near parallel alignment, not showing twinning like 'spearhead marcasites. There appears to be some dissolution and maybe redeposition to produce the steps.
The hexagonal appearance could also be due to spinel contact twinning. Magnetite does form in such hexagonal plates. if so these steps might be polysynthetic.
Kostov in Crystal Habits of Minerals writes of platy magnetite and conditions that seem to make for that habit, but I'm not sure anything he mentions would apply to this.

[Philippe Durand]

Ok thank you Jordi
So I am the owner of a Moroccan magnetite; cool.
Thank you for the explanations Bob.

Now I have to find a Nador Hematite :)

[Philippe Durand]

:)

[Philippe Durand]

:)

[Philippe Durand]

gwindel

[Michael Shaw]

[Tobi]

Very fine indeed! Such a transparent and lustrous gwindel is a treasure for every quartz collector like me, and that it's from Mt. Blanc makes it even more desirable. And though I like older finds with a "classic" touch, I love the fact that this is a recent find from this summer!

Great piece, Philippe!