FMF - Friends of Minerals Forum, discussion and message board

[Jordi Fabre]

Ignacio published in the Spanish Forum a request without answer yet. He would like to know which is the specific twin of this Rutile. Someone can help?.

[Jordi Fabre]

[Jordi Fabre]

Another image of an eightling twin.

[Jordi Fabre]

Here them are the other views.

[John S. White]

It looks very much like a twin to me. I have seen similar ones from Graves' Mountain, Georgia, USA.

[jimB]

I checked my meager print resources and did not find a match so that I could say " it's a this one or a that one". I am a closet rutile buff as well and look at them when I can. I'm no scientist but I love symmetry. This one sure looks twined to me,

[keith]

Hi

Firstly: Are you sure its rutile and not cassiterite?

Cheers

[Jordi Fabre]

Sure, it is a classic Spanish locality for Rutiles. Not Cassiterite there.

[Pete Richards]

With these additional pictures, I agree that it is a twin. As John White commented, similar twins are found at Graves Mountain in Georgia. The twin law is {011}. The twinning causes the crystal morphology to develop unevenly, and it is very difficult to determine by examination how the morphology is related to that of untwinned crytals. Twins with a pseudo-monoclinic morphology that look a bit like dark brown gypsum crystals are common at Graves Mountain. I have also seen similar twins from several other locations in North America.

These twins usually are flat, and don't zig-zag like the one posted above, from Magnet Cove.

I attach images of several examples from my collection. They differ from the Spanish one in having only one point. On the first one, the boundary between the two halves of the twin can be seen by a change in the reflection on the large face.