MINERAL IDENTIFICATION KEY II

by Alan Plante, Donald Peck & David Von Bargen

We wish to make this key available to one and all in the hope of correct identification of minerals in collections, rock gardens, and on windowsills everywhere. You may copy it, or any part of it, for non-commercial, personal use.

We thank Lloyd Brown, David Jacobson, and Alfred Ostrander. Their excellent advice and encouragement in this project was extremely helpful. ©2003, Alan Plante, Donald Peck, & David Von Bargen. In cooperation with Mindat.org.

Table of Contents

This Mineral Key is designed and intended for use on-line.

or website databases such as Mindat, Webmineral, or the MSA's "Handbook of Mineralogy" in order

Unlike most keys for wildflowers, this system for the identification of minerals is limited – both in scope and applicability. Only a couple hundred of the most common or "usually seen" mineral species are covered. Users may well come across rare species which are not covered here. The system also requires good enough samples of the minerals to perform the tests in the sections describing mineral species. It is probably not useful for the identification of micro-crystal samples. Still, it can help narrow down the search by eliminating the more common species as possibilities. If a sample of some unknown mineral does not "key out" to one of the common species, then further testing and research to determine its identity might be worth while. But the user is cautioned that every possible effort should be made to key the sample out using this Key before looking elsewhere for help. Many common minerals have varied habits and other characteristics which might lead one to suspect a sample to be something rare, when in fact it is a common species in one of its less-prevalent forms. A careful examination of guide book information may allow one to identify the unknown sample. Resorting to such things as sending samples in to a lab should be the last thing one does with an unknown. You should be quite certain that it is a rare species, one not covered here or in a mineral guide. Tests should be done on a fresh and unweathered surface if possible (don't break a good crystal, when an inconspicuous surface will do for testing).

Often a single series of tests may not key the user in to the correct identification. The odds of making a correct identification will be increased if tests are repeated. Take several streaks, especially if a sample is proving difficult to get a streak from, test the hardness more than once – and do tests both ways, trying to scratch the known hardness tool with the mineral and trying to scratch the mineral with the tool. If possible, when examining samples for cleavage, look at several samples – and try to use fresh breaks, cleavages which you – not nature – have produced. It is often a good idea to examine small cleavage surfaces using a 10X lens. If the first try at determining a hardness is unsuccessful or ambiguous, perhaps the second, third, or fourth will do the trick. The same holds for other tests. Such diligence to repetitive procedure usually pays off where a single try does not.

Finally, if the first run through the tests doesn’t seem to be leading you to the correct identification – try again from scratch. A second run through the entire procedure may do the trick – maybe rethinking some aspect of the tests, such as whether or not the sample really has a metallic luster. In the end, care should lead one to the correct identification for species covered in this Key. Also, practice may not always make perfect – but in the case of mineral identification the more you practice the better you will get at it. So try running samples of known species through the procedure to get a feel for how the key leads one step-by-step towards an identification. Practice, practice, practice…