FMF - Friends of Minerals Forum, discussion and message board

[alfredo]

And how will you know the crystal is bounded on all sides by faces if it is still partially embedded in an opaque matrix? "Euhedral" is just an assumption unless the crystal is removed from its matrix.

[John S. White]

Of course, Alfredo, and I assumed we were talking about floaters in this context. That is, crystals free of matrix.

[Jordi Fabre]

I publish myself a message from Konstantinos. He had some troubles with our antispam system, so, helping him I fixed it and publish it now:

Hello all!

I've heard a lot of mineralogists argue about the term floater which seems to be a mineral collector/dealer term.

I'll try to give a definition of what I THINK it IS. I would also like to suggest some ways of how I THINK it is formed. I say THINK, because I am not a mineralogist myself and the term is not officially defined yet, to my knowledge.

So, floater for me is a SPECIMEN (single crystal OR cluster of crystals of one or more different mineral species) that is TERMINATED all the way around, with no contacts of missing crystals, on all surfaces, at its pristine condition.

Respectively, Spanish Pyrite cubes ARE floaters, because they are terminated all around, although they came out of a matrix rock. Also, a matrix specimen can still be a floater, if the matrix crystals are terminated to the visible surface of the specimen, although separate crystals are terminated.

Single crystals, according to my definition are not floaters, unless they are terminated on all sides.

In my definition I mention: "at its pristine condition". Clarifying that, I would like to say that a seriously damaged specimen (I'm talking about contact(s) of now-missing crystal(s) or broken termination, not chips and dings) can still be a floater, if it was a floater at its undamaged condition. For example, if a cluster of Quartz points that was fully terminated once, and so a floater, has small contact of a missing crystal or/and a broken crystal, is still a floater, however, a damaged floater.

How floaters form:

1-If a single crystal or a cluster of connected crystals of one or more mineral species, for some reason (for example,vibration) leaves the matrix rock and then regenerates at the point of attachment to the matrix rock, then it becomes terminated all around, so a floater.

2-If a single crystal or a cluster of connected crystals of one or more mineral species leaves the matrix rock and then crystals of different species form all around, then the whole specimen is terminated all around, and so a floater. This one would be a matrix piece and still a floater. To visualize this, imagine a singly-terminated Quartz point, broken off of the matrix rock and then Calcite crystals grown around the broken bottom and cover it. You have a nice matrix floater specimen. In this case, the Quartz point was the matrix, since it was formed before the Calcite crystals.

3-If a single crystal of a cluster of connected crystals of one or more mineral species that is/are terminated on all visible sides are partially or fully cover by matrix rock, which is later removed (chemically,mechanically), the new specimen is terminated all around, and so a floater.

That's it! If I am mistaken in anything I write due to miss of mineralogical knowledge, please forgive me and correct me.

All the best!
-Kostas.

[John S. White]

In general, I believe that Konstantinos has provided a quite reasonable definition of the term floater, as it applies to mineral specimens, EXCEPT for the part copied here:

"For example, if a cluster of Quartz points that was fully terminated once, and so a floater, has small contact of a missing crystal or/and a broken crystal, is still a floater, however, a damaged floater."

The problem with this is that one cannot know if the damage represents a former connection to additional crystals of the same or different minerals, so one cannot be certain that the specimen was ever a true floater.

And, there is a very fine line between a crystal showing no contacts all the way around, and a crystal that has a microscopic contact that now cannot be observed because it is so tiny or there is no evidence of it to be seen. What is the difference between a crystal that grew suspended on a fiber and the fiber has been removed so that the contact does not show, and a crystal like the Spanish cube-shaped pyrites that grew in total contact with their matrix? This may be an artifical distinction, and an unnecessary one.

In my own collecting I prefer to call crystals floaters if they appear to be floaters, and I do not attempt to make the conditions too rigid. After all, I only have to satisfy my own conditions, and I find that they are at least slightly flexible. If I am a dealer and I am selling a crystal that I believe is a floater, then perhaps I have to be a little more careful in my definition.

[Konstantinos Ch.]

Hello again!

This is to thank Jordi very much for fixing and posting my reply and to make some additions.

Is a specimen with tiny literally microscopical contact(s) a floater? No , it's not, but it should be valued only a little less, in my opinion, of course considering the rest factors of valuing a specimen. A dealer should inform the clients about the contact(s) , no doubt! But we like floaters because we see the fully terminated crystals all around and they look good in our case of display. So,if you care about the display, it is technically a floater. If you are too strict, then don't pick the piece.

Is a naturally etched or naturally polished crystal a floater? Yes, if it was terminated all around before it gets etched or polished. However, this is hard to understand when a crystal has suffered that conditions. The important is that it looks the same all around now and it can "work" as a floater in any case, showing etching instead of terminations.

Rarity? I really don't know... I guess it depends on the locality and the material. Using the Spanish Pyrite Cubes again as an example, I will say that floaters from this material are more than common. The dealers prefer to repair the crystals back to matrix than selling them as free standing floaters. Certainly, the term itself doesn't indicate the rarity of the piece.

What is for sure is that being a floater is not always an advantage for a specimen, but it's always something better than a disadvantage.

Any comments would be very welcome!

Take care!
_Kostas.

[Konstantinos Ch.]

Hi once again!

John, thank you for your comment. I was sure someone would comment this one! John is right, we cannot be sure. But, sometimes, unfortunately, our own floaters may get damaged and a crystal could be removed and leave back a contact. We should still know that we are holding a floater, unfortunately, a damaged one.

Also, when a dealer sells a ball cluster of massive Sphalerite at 10 x 10 x 10 cm covered with Quartz points with the biggest measuring 0, 5 cm , and the specimen has a missing Quartz point, I don't see why shouldn't we believe the man the piece is a (damaged) floater. In such cases it is far less possible that the missing crystal was actually the link to another part of the same specimen.

And to clarify something: When I say contact, I mean contact between two crystals two at a time) of the SAME mineral species. And I mention only this type of contact because it's very typical for each species.

All the best!
-Kostas.

[Peter]

I would think that the word schwimmer or english floater is a practical term (and not entirely genetical) which originated from miners/collectors finding loose crystals, crystal groups or crystals on matrix (with crystallization all around) for instance in an cavity, perhaps chock full of specimen, pocket sand or clay or also with open space. Many pockets to have a big portion of open space. This cavity may have been in a hydrothermal ore vein, a pegmatite pocket, an alpine cleft or a augite crystal found loose in a farming field in the Eifel region of Germany.
Strahlers (crystal seekers) have been active profesionally since the 1400s in Switzerland and perhaps the name originated here.

Many alpine clefts and pegmatite pockets have open space and it is not rare to find some specimens laying loose with no obvious poit of attachment. They may or may not have been formed originally in a medium in a medium not in contact with the pocket walls. A floater may also consist of a specimen found " floating" i.e. loose from the pocket walls where for instance a once pocket wall plate detached and recrystallised, a single crystal shattered and recrystallised although an "ideal" floater is truly well and fully developed in all directions and is laying loose in a pocket or embedded in sand, pocket clay etc. Now, often there may be some other minerals, mica, clay minerals, fibreous minerals etc attached in some spots and this may or may not be a point where the specimen once was truly attached (by crystallised minerals) to the pocket wall, floor etcetera which may be impossible to know for sure even if you dug that specimen out of the pocket yourself.
In the Navajun deposits I do not know of open pockets with floater crystals. Yes, they are euhedral (I think really most are) but sitting in matrix broken out of other matrix I would not call them floaters.
Pockets with pyrite may occur in other margo or limestones of primary pocket origin (i.e. formed during some event.... where minerals crystallised or re crystallised( or of secondary origin i.e. for instance formed by later weathering or dissolution processes. Example water flow in a fissure and in some places dissolving encapsulating margo, limestone etc. It is not uncommon to find pyrites in such conditions. These may be floaters, laying loos in the pocket.

For instance the Karelia beryl mine in Finland is a large pegmatite with several crawl in size pockets, some of them with large floaters smoky quartz crystals. Most of the gem beryls (green to golden) were here found frozen in matrix in the pocket! That is the entire pocket was filled with recrystallized feldspar, mica, beryl, and Fe ox hydroxides etc. Once removed one would be tempted to call them floaters but most of them really were not (i.e laying loose in the pocket) although in a few instances this was the case.

The Himalaya Mine in California has produced numerous pockets which have been chock full of crystals with just some tiny open spece inbetween just enough to barely be able to gently wiggle out crystals without damaging them or the atached cleavelandite/lepidolite/quartz. Many of them are true floaters, tully developed in all directions, not attached by crystallisation but perfectly wedged inbetween others alike.