FMF - Friends of Minerals Forum, discussion and message board

[Bob Carnein]

Thanks to Mr. White for his comments. To me, growth dislocations produce what look like fractures--they even have conchoidal markings on their surfaces. Perhaps "fracture" is an inaccurate term, but the dislocations apparently produce stress that results in a thin surface of dislocation. Perhaps this is a semantic quibble.

With regard to Mr. White's second comment, I was speaking from my personal experience. I have 2 beryl crystals with helical dislocations in my own collection and have seen several others offered for sale at shows. However, I have not seen similar topaz crystals personally, and I have only seen a few on Internet sites--including the FMF Forum. No doubt, Mr. White has more experience with these "inclusions" in topaz--I congratulate him for being fortunate enough to own several such crystals! BTW, I don't like the word "inclusions" for these fascinatng structures because, to me, the term implies the presence of some foreign material. The helical structures in my crystal appear to be empty.

[John S. White]

I no longer have my collection of crystals with spiral inclusions but it consisted of three beryls, six spodumenes and seven topazes. Under high magnification one can see that at least one of them, a beryl from Brazil, does not consist of fractures. in fact, none of them do.

[John S. White]

I should say that the inclusions in beryl photo I posted seem to be atypical. Those in a topaz from Mason County, Texas, are far more typical. See attached photo.

[Bob Carnein]

Those don't look at all like the structures in my topaz. I'll try to get a better photograph, but I admit that I'm challenged in that department.

[Bob Carnein]