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tremolite or actinolite?

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 Can anyone help with the recognizing of the samples - tremolite or actinolite??? Color from green to very deep green (almost black in spots), very dense crystal but some fibers -asbestos visible at ends (close up). btw; got it on e-bay as kyanite :-) Thank you

asked Oct 9 by peterbukowski (200 points)
edited Oct 10 by peterbukowski

3 Answers

0 votes
Looks most like kyanite, do you have reason to believe it is not?
answered Oct 9 by Weasel (38,360 points)
Of course, it has flexible asbestos fibers sticking out (see the close up) and the crystals is different. It's tremolite family, no doubt.
0 votes
I think I found the answer, if anyone is further interested...

"Tremolite has a greater presence of magnesium over iron, whereas Actinolite has a greater presence of iron over magnesium" (minerals.net)

"Pure magnesium tremolite is creamy white, but the color grades to dark green with increasing iron content" (wiki).

Conclusion: These samples are deep green indicating high iron content prevailing over magnesium, which would further indicate Actinolite with greater presence of iron over magnesium.
answered Oct 10 by peterbukowski (200 points)
0 votes

Mystery solved.... this is ferro-actinolite very high iron content comparing to other family members, this is the reason for such deep green color

ferro-actinolite: Ca2(Mg2.5-0.0Fe2+2.5-5.0)Si8O22(OH)2 ,  most likely origin location Montauban, Quebec, Canada

vs tremolite Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2

vs actinoliteCa2(Mg4.5-2.5Fe2+0.5-2.5)Si8O22(OH)2


answered Oct 10 by peterbukowski (200 points)

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