Identification

Step 1

The first step of the identification process involves determining the luster of your unknown. Remember there are numerous types of lusters, but for identification purposes it is generally sufficient to distinguish only between metallic and nonmetallic minerals. Look at the images below. Which does your specimen most closely resemble? Metallic minerals have the sheen of a metal, like the frame of your desk. Nonmetallic minerals may appear glassy, meaning they allow light to pass through, dull or even waxy. Keep in mind you are not looking at color, simply the way a mineral specimen reflects room light.

There is one concern, many metallic minerals contain the element iron. When iron is exposed to oxygen in the air it starts to covert to an iron oxide compound we commonly call rust. Rust dulls the metallic luster of most minerals. If you have a sample that has been in your science collection for a few years it may have been shiny when new but has dulled with age (kind of like a "old" copper penny. That can sometimes make it difficult to be certain if a mineral has a metallic luster or not. There is one trick you can try. Take your streak plate and gently rub the mineral on the plate. If it leaves a very noticeable colored or black streak it is probably a metallic mineral. Note:If you rub any black mineral hard enough it will leave a black streak whether it is metallic or not, but you will find the nonmetallic minerals require a much greater effort to make a black streak!

When you have made your decision click on either the nonmetallic or metallic button.

| BACK |