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Mineral identification tips
  
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Robson Vieira




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PostPosted: May 16, 2024 16:40    Post subject: Mineral identification tips  

Hi everyone. Dueling about to distinguish a sample between topaz and euclase I have faced with the question of the cleavage of each one, and with the highly technical subject of Miller indices of cleavage planes. Euclase has the clinopinacoid (101) perfect cleavage direction as the topaz has the basal (001), if I'm not wrong. I would like to ask you all to explain in practical terms what I need to know about cleavage planes and Miller indices to help me to identify crystals. I have the basic experience with different types of cleavage, but I would like to be confident with the numbers of the literature. Is it really needed to study crystallography? Anyone know a practical guide?
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Robson
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Bob Carnein




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PostPosted: May 16, 2024 17:12    Post subject: Re: Mineral identification tips  

Whether it's necessary to learn about crystallography depends on how serious you are about adding to your identification skills and whether you care about the "whys" of many mineral properties. Crystallography is a great help for those who want to develop some level of independence, in which they don't have to constantly rely on others for help. It also allows a collector to communicate clearly with those who already have such skills. No one has to know crystallography in order to collect minerals, but that knowledge also helps you to evaluate specimens that are offered to you for sale or trade.

Learning Miller indices and the fundamentals of crystallography are not easy tasks for the beginner. The best way to learn is to look for a class or course in which you can obtain "hands-on" experience, working with models and then with natural crystals. Being able to ask questions and get clear answers and to work with friends who are also struggling with this is far better than trying to wade through by yourself. You may find, also, that a light introduction is not very satisfactory--you need to immerse yourself in the subject for a period of time. I recommend a college class, if you can find one. If you are an independent learner, I recommend trying a text such as an old edition of Dana's Manual of Mineralogy, which does a good job introducing the basics. However, interpreting pictures in a book or on a website won't provide you with the knowledge you can obtain from a hands-on class.
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lluis




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PostPosted: May 17, 2024 10:25    Post subject: Re: Mineral identification tips  

Hi

Euclase is known because it can mimic practically all.
I would suggest asking for an analysis.
Hardness of topaz is higher than euclase (8 to 7.5), but the density of euclase is lower than topaz (2.99-3.1 versus 3.4-3.6) ... If you can measure such....

With best wishes

Lluís
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Jordi Fabre
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PostPosted: May 17, 2024 16:20    Post subject: Re: Mineral identification tips  

Bob Morgan wrote:

I hope you don't have to cleave the specimen to identify it.
One simple suggestion is to examine the prism faces. This area of euclase crystals is usually more striated, although this is only a hint, since topaz crystals can on occasion have similar striations.
Check out and compare photos on Mindat.org

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Josele




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PostPosted: May 18, 2024 09:12    Post subject: Re: Mineral identification tips  

I tried to explain how Miller indices work here:
https://www.foro-minerales.com/forum/viewtopic.php?p=151654#151654 (in Spanish).
Maybe this can help...
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Robson Vieira




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PostPosted: May 20, 2024 15:24    Post subject: Re: Mineral identification tips  

Hi guys. Im very glad your attention at all. It was more clear than i spected. Thanks a lot.
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Robson Vieira




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PostPosted: May 20, 2024 15:32    Post subject: Re: Mineral identification tips  

Hey Josele. Yeah guy, i have token a look and it is complete and handy. Thank you.
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Robson Vieira




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PostPosted: May 20, 2024 15:37    Post subject: Re: Mineral identification tips  

Jordi Fabre wrote:
Bob Morgan wrote:

I hope you don't have to cleave the specimen to identify it.
One simple suggestion is to examine the prism faces. This area of euclase crystals is usually more striated, although this is only a hint, since topaz crystals can on occasion have similar striations.
Check out and compare photos on Mindat.org


What a advice! Thanks
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Robson Vieira




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PostPosted: May 20, 2024 15:43    Post subject: Re: Mineral identification tips  

Bob Carnein wrote:
Whether it's necessary to learn about crystallography depends on how serious you are about adding to your identification skills and whether you care about the "whys" of many mineral properties. Crystallography is a great help for those who want to develop some level of independence, in which they don't have to constantly rely on others for help. It also allows a collector to communicate clearly with those who already have such skills. No one has to know crystallography in order to collect minerals, but that knowledge also helps you to evaluate specimens that are offered to you for sale or trade.

Learning Miller indices and the fundamentals of crystallography are not easy tasks for the beginner. The best way to learn is to look for a class or course in which you can obtain "hands-on" experience, working with models and then with natural crystals. Being able to ask questions and get clear answers and to work with friends who are also struggling with this is far better than trying to wade through by yourself. You may find, also, that a light introduction is not very satisfactory--you need to immerse yourself in the subject for a period of time. I recommend a college class, if you can find one. If you are an independent learner, I recommend trying a text such as an old edition of Dana's Manual of Mineralogy, which does a good job introducing the basics. However, interpreting pictures in a book or on a website won't provide you with the knowledge you can obtain from a hands-on class.

Hi friend, and thanks for your attention. In fact, I have a degree in Math and I have studied symmetry operations in Linear Algebra and vector calculus. I expect to perform a crash course in crystallography, but I wanted to know your opinions about what is really needed to understand the topic via intuition and practical means because the subject has a large amount of non-theoretical approach. I guess you are right, a practical workshop with real crystals and a tutor would be more than ideal.
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cascaillou




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PostPosted: Jun 01, 2024 07:40    Post subject: Re: Mineral identification tips  

If the crystal is loose (i.e. free of any matrix and without associated minerals) and not too small (weighing at least 3g) , then you may measure specific gravity using a scale with 0.01g accuracy. Indeed specific gravity is not the same for topaz (3.51 to 3.58) and euclase (2.99 to 3.18).

There are other possible look-alike minerals, though (danburite for instance)
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