Identifying Minerals
Posted by: Raymond McDougall on 11.26.2013 | Filed under: Beginners

If you want to build a collection of minerals and truly enjoy minerals, you need the confidence to be able to identify different minerals. You will start to learn more about where different minerals come from. If you become a dedicated collector and read a lot, you may even become knowledgeable enough to be able to look at some mineral specimens and say approximately when the specimen was collected. Eventually you may even become someone who can sometimes look at a mineral specimen and even name the pocket it came from – yes, it happens to those of us who truly love minerals.
But we all start at exactly the same place, where we don’t have much knowledge at all and we decide we want to really learn about minerals. If you haven’t already read it, see Seven Easy Things You Can Do to Start Mineral Collecting, and if you have already read it, you’ll note that several of the steps there involve interaction with minerals themselves, and learning about those minerals.
The single most fundamental skill you require, if you want to challenge yourself to become a mineral collector, is the skill to identify minerals. There are basic identification skills we all learn – they are simple and become second nature. You will eventually know so many of the minerals visually that you won’t have to test almost any of them, but in the beginning, there is nothing better than starting with the basics, and working through them with some test minerals, so you get a feel for it.
Any good book, such as a field guide or a text, which includes a discussion of the fundamentals of minerals or mineral collecting will do an excellent job of explaining specifically how to identify minerals. I list a few at the end of this post. And my suggestion is don’t just read them – read with minerals at your side. This works best with things that are rough, not pretty, and not perfect – often, something you collected yourself. Conduct the standard tests the books describe.
Test out scrap pieces. Do hardness tests on parts you don’t mind scratching. Make sure you can see and distinguish the cleavage of the minerals, colour, lustre and degree of transparency/translucency/opacity. Specific gravity is another test that can really help with identification. My friend (and well known long-time mineral dealer) John Betts has posted a great article on specific gravity testing on his website – if you’re going to test SG, read this first! Streak colour can help with certain minerals. If you have crystal faces on your test specimen so that you can identify the crystal shape, that will be extremely helpful (don’t be fooled though – perfect cleavage shapes can sometimes look like crystal faces and shapes).
Once you have an idea of the test results, look at any decent identification key (also sometimes called “determinative tables”) – these can be found in field guides, texts and online. One good online example is here, and looking on a search engine will lead you to more fine ones. So, for example, if you have conducted your tests using the book, and you have determined that you have a specimen of a mineral that is non-metallic, cream coloured, translucent, with vitreous lustre, perfect cleavage in the form of a rhombohedron, and a hardness of 3, you can line all those properties up in an identification key and land at calcite, or maybe a similar mineral (more specific information may help to distinguish – the devil can be in the details).
Try it out on different kinds of things, or, if you have bought minerals that are already identified, examine them together with the descriptions in field guides so that you learn what the different terminology means and can see the characteristics being described. This kind of practice will very quickly train your eye to make distinctions and begin to make identification very straightforward for you.
I would go so far as to say that mineral identification is the test that will tell you whether you are truly interested in minerals. I see so many postings of poor quality photographs to online mineral forum discussions with the question “what is this rock?” and providing no other diagnostic information. Each posting suggests to me that, sadly, the person posting the photo is not really interested in minerals. There is challenge and fun in learning and working with rocks and minerals – if a person does not have even the interest to open an easily available book and try, or to type “mineral identification” into Google and look around a bit online before pulling out a smartphone and interrupting the world at large, serious mineral collecting is probably not for that person. (As an aside, it is usually not possible to identify a randomly collected mineral from a photograph – you need the information from the basic diagnostic tests to be able to distinguish enough to make an identification.)
However, if you have made it this far reading this, you are thankfully not a lazy smartphone person, and I am happy to be able to tell you that mineral identification is fun, becomes easier to learn as you go, and has never been easier, given all the amazing resources we have at our fingertips. So as you do the Seven Easy Things You Can Do to Start Mineral Collecting, make sure you develop mineral identification as a core skill. Once you learn it you never lose it, and it will help you know when a mineral specimen is worthy of your collection.
Excellent General Books and Field Guides
Sinkankas, John. Mineralogy for Amateurs (1964) (D. Van Nostrand Company Inc.) My favourite general mineralogy book – written for non-professionals with real interest in learning about minerals, this book explains the essential concepts in an engaging style.
Pough, Frederick H. A Field Guide to Rocks and Minerals (1998). Peterson Field Guide Series (Houghton Mifflin Harcourt) Most mineral collectors have a copy of this classic field guide!
Hurlbut, Cornelius S. and Klein, Cornelis (after J.D. Dana). Manual of Mineralogy (currently, in its 23rd edition, this is Dutrow, Barbara and Kelin, Cornelis, Manual of Mineral Science 2007). (John Wiley & Sons Inc.). My 20th edition has Appendix I – Determinative Tables – which were very helpful before the days of online mineral identification keys. This is the evolution of the original text by Dana, first published in 1848, and is to this day the classic used in introductory mineralogy courses in university. Lots of great information, this is a university-level text written about the science of mineralogy, and also including lots of fine descriptions of minerals.