FMF - Friends of Minerals Forum, discussion and message board

[John S. White]

Alfredo: I don't know the answer to that as I have very little experience with Raman which was not available to me when I was at the museum. The fineness of the crystals in this case might be more of a factor in preventing a reading and you also have to find someone with the instrument who is willing to take the time to identify something like this. One more thought, The nature of the crystals in this case also suggests, to me, goethite and not hematite.

[marco campos-venuti]

John, is it possible to distinguish fibrous Hematite from fibrous Goethite with the naked eye? I mean not included in quartz but when they are in botryoidal shape. I suspect there is a bit of confusion, almost I'm not sure to understand the difference.
Usually inclusions in quartz are considered Hematite when flat (also elongated) and Goethite when strictly fibrous (for example the material that was sold as quartz with cacoxenite and looks to me as Goethite).
I'm sure Raman doesn't work on most inclusions in quartz, mainly because quartz strongly replace any included mineral.
I can post many examples from my collection.

[marco campos-venuti]

Few examples of what I suppose is Hematite in Quartz. Mostly red, main characteristic is a flat crystal, more or less elongated.
All sample are from Brazil, difficult to say the exact place. How would say Rock Currier, probably Minas Gerais.
Last picture is an Amethyst Brazil Twin.

[marco campos-venuti]

And here few examples of what I consider Goethite in Quartz. I'm not sure, just is what I use to call it. Mostly yellow and strictly fibrous, more abundant in Amethyst. All samples from Brazil.
The last is the material still commercialized as Quartz with Cacoxenite, but most people know is not. Similar but a phosphate.

[marco campos-venuti]

And here is what we call Quartz with iron oxides, because we don't know what it really is. Also from Minas Gerais

[Josele]

[marco campos-venuti]

It is from Rome!
(We are joking, come back to the topic please)

[Pierre Joubert]

Beautiful pictures and a lovely topic.