FMF - Friends of Minerals Forum, discussion and message board

[stumpy]

Has anyone ever thought about why minerals occur in such a wide variety of colors, and indeed, why there is such a large number of different mineral species? The sheer diversity of plants and animals and their colors can be explained by evolution, but what about in the case of minerals?

[alfredo]

Several tens of common elements, combining in many different ways depending on an infinitely variable combination of temperatures, pressures, oxygen levels, geological processes concentrating certain elements above their common abundance, plants and animals concentrating certain elements... etc. I'm rather surprised by the opposite view: why only 4,500 species? Why not 9,000? Well, wait a few more years... there will be!

[stumpy]

I guess the question is, why do they need to be such bright colors and in such attractive forms, since we humans are the only ones capable of appreciating their beauty and it serves no practical purpose. Surely it would be just as easy [and no doubt you would prefer it :0) ] if they were all black?

[mmauthner]

I have never really thought about colors that way. I have, however, given some thought to some sort of natural selection going on in terms of habit. I was collecting calcite crystals in southern Alberta and observed that in the same system of viens and pockets that the calcite crystals occurred in several habits, but the the habits were related to the shape and "style" of the cavity they grew in. Not separate cavities, but contiguous ones that widened, narrowed or otherwise changed shape along the way. Makes one wonder.

Mark

[Elise]

It might be interesting to refer to the writing/seminars of Robert Hazen on the concept of evolution in minerals, part of which points to a connection with evolution in biological systems: "2/3rds of known mineral species on Earth probably could not have appeared prior to the origin and evolution of life." I was disappointed to have missed a seminar he gave nearby - I understand that controversy runs high over this, but coming from a background in biological sciences, I find the idea intriguing. For a brief overview, see the February 2010 issue of Elements magazine which was devoted to the topic with articles by Dr. Hazen and others.

But back to color in minerals, perhaps the colors are only coincidental to an underlying evolutionary type of process selecting for other factors. If in the formation of a planet at least some portion of the minerals owe their existence to biological activity, I don't think humans (ie mineral collectors) had much impact on the selection process by that time.

Elise
Sidebar - not all of us rely on sight for appreciation (I am thinking about an old article in Lapidary Journal on development of a museum mineral exhibition for the blind ).

[Eduardoo]

I have a lot of trouble understanding what evolution of minerals means. In fact I don't think the expression can be used at all, at least not in the sense as evolution works in living beings.

Minerals do not produce offspring similar to their progenitors but not exactly equal to them, nor more minerals are born than there are resources needed to support them, so no natural selection can act on them.

Maybe the mere existence of life and it's evolution could have an impact on the relative abundance of some minerals compared to others. This is an intriguing idea, new to me, and I feel very curious about it.

One thing that caught my attention in the mineral word, was the designation of "species" to the different combinations of elements that constitute a mineral. It shocked me at first but now slowly I am getting used to it.

Evolution is a specific term with an specific meaning in the biological sciences. All attempts to extrapolate it's use in sociology, astronomy, mineralogy!!! usually fail.

Just one comment about mineral colors. Why are they not all black since humans are the only begins that can appreciate the beauty of their colors? Well, nature seems to act pretty indifferent to what humans like or dislike. Mineral colors are not there for us any more than the rainbow colors are. If we find them beautiful or ugly, well, that's us, not them.

(I am sorry if my imperfect English obscures some of the concepts)

Regards,

Eduardo

[nurbo]

Hi all,
Ill throw my hat in the ring with this .......

Colours are created by the selective absorbtion and reflection of light of differing wavelengths, Ive often thought about minerals being different colours within the same species, its always (As far as I know, Im happy to be corrected on this if Im wrong) an addition (or subtraction) of a component which in some microscopic sense changes the shape of the surface of the mineral so it absorbs and reflects a slightly different wavelength of light. The idea that minerals derive some kind of benefit from being different colours is quite odd to me, after all they form in the dark and the vast bulk of Earths minerals remain in the dark which brings in the old arguments about whether things have any colour at all unless exposed to light?
Plants look mostly green in colour, this is because the only wavelength of light the plant doesnt actually use for its own benefit is the wavelength we call "Green" so hence it is reflected away from the plant and when we look at it it appears green, I cant believe that minerals which form underground in the darkness are reflecting light waves which are of no use to them, if they were it would imply that minerals had an intelligence and in some way worked to a plan, I personally believe they dont and that any colour we may see them to be is purely coincidental.

b

[Tobi]

[Antonio Alcaide]

In spite of Elise's words about evolution in the mineral world, I agree with nurbo: that idea could not be extrapolated from living beings to minerals. The natural selection has sense only when life is involved. Minerals, as far as I know, are not live. They have not to struggle for life, for limited resources, so the habit, the composition or the color would be advantages.

Chemistry and Phisics are ruled only by chance and necessity -remember Jacques Monod's famous theory and book-. Color is an accident. Minerals do not mind man's eyes. I know it is suggestive to place man as the centre of the universe, but it is an old-fashioned idea. :-)

On a deserted Earth minerals would show colors as well. Are black the minerals in a remote planet at the end of a distant galaxy? I am afraid not.

Stumpy, with his -why not 'her'?- refined English I cannot equal, has suggested a fairly interesting question. Interesting but in my opinion deceitful.

Regards

[Elise]

[Peter]

I did not read the article referred to yet, but I understood it is about the different environmental; stages in the earths development, the creation of the atmosphere, biosphere and the subsequent environments for mineral formation. If the atmosphere and biosphere had not developed many types of environments creating many secondary and colorful minerals would not have happened at least in the way and during the time spn it did and does.
Many bacteria and other organism also humans of course gather and concentrate different elements forming mineralisations (bones, teeth, magnetite for orientation/navigation etc). Now also the biological evolution obviously occured for specific elements and their combinations available on earth. Mineral comsuming bacteria is common and found in for instance granites in rather great depth in boreholes, some forst biological life is believed to have formed on the very surface on mineral grains, crystals. Hydrocarbons, for instance even huge masses of Kerite in chamber pegmatite pockets in Volodarsk, Ukraine have a very regular structure very close to proteines. I have described hydrocarbon pocket pegmatite, in fact a new class of pegmatites in ZWMO in 1997 (I found them already in 1977). Interesting is the occurence of not only hydrocarbons in pockets but the occurence in small cavities in the graphic structure around cavities.