FMF - Friends of Minerals Forum, discussion and message board

[MountOlymp]

I found this on a mountain in Rodope while walking a path. It's a pink and a red almost scarlet color with some black spots that look sort of like flattened metal from a first guess. Specific gravity test results pink - 2.64, red - 2.66. Scratch, magnetic, and effervescent tests result negative. Semi-transparent unpolished as found.

[Pete Richards]

Perhaps I am geograhically myopic, but where is Bilula? Where is Rodope?

[Tobi]

I would not suggest some random rocks on a path to be beryl, rather quartz. If you say the spec. gravity is at ~2,65 - this is exactly the gravity of quartz. Sure, beryl has a similar gravity but such rocks with 2,65 are most likely quartz. If beryl, it would scratch quartz, maybe you could try this ...

[Pete Richards]

Another good candidate would be feldspar.

[Tobi]

[MountOlymp]

I tried scratching it with quartz but nothing happens. I find the crystal is coherent with other beryl online photos and most quartz is massive not in crystal shape. The massive quartz rock is scratched by this.

[MountOlymp]

The quartz piece I used to scratch is glass clear and has exactly 6.5 sg. It is scratched by the red and pink stone.

[MountOlymp]

[MountOlymp]

[MountOlymp]

View from side

[Michael Shaw]

First, these are not crystals, so there is no twinning here. It is very difficult to identify rocks/mineral from photos, especially photos that are not clearly focused. That said, I agree with Pete Richards, that the lighter-colored stone in the first photo may be feldspar. The flat portions are not crystal faces, rather they appear to show cleavage typical of feldspar. The specific gravity of the most common feldspars varies from 2.55 to 2.65 so this could be a possibility.

The reddish-colored stone in the first photo looks like quartz, and your specific gravity measurement tends to support this. Hardness tests are difficult to do without known, standardized samples to test with, so I'm afraid your hardness tests may be inaccurate.

If you really want a definitive answer as to what these stones are, I suggest you take them to a geology department at a nearby university, where someone can examine them firsthand.

[MountOlymp]

I'm sorry that you can't see the crystal habit structure of red crystals. And the obvious twinning or rpitax of the second red.

[Peter Lemkin]

[SteveB]

I think what you call crystal twining structure etc is just cleavage planes and pretty sure all examples are feldspar variant which has two cleavage planes. Get a set of hardness scribes to get an hardness measurement, never use random stuff as a measurement test. Its a rough guide for field testing for beginners and not a tool anybody ever uses, they use the correct tool for the job.

[Bob Morgan]

Beryl doesn't twin except at the unit cell layer scale.