Hello fellas ;) <3!
I hope you are all doing well! :D.
The first example that I bring you and maybe the most alarming is related with the word Coal, because a lot of people (even geologist) say that coal is a mineral (¿WTF?), and this is totally incorret, because coal is a rock and it can't be called mineral, for the simple reason that it doesn't fit in the definition of mineral, which is:
¨A Mineral is a body produced by the processes of inorganic nature, having a definite chemical composition and, if formed under favorable conditions, a certain characteristic molecular structure which is exhibited in its crystalline form and other physical properties.¨ (Dana, E. 1997)
So with this concept on mind, we can understand that a mineral has to have at least three characteristics:
- Be originate by a process of inorganic nature (not organic)
- It has to have a definite chemical composition
- It must to have a molecular structure defined (crystalline structure)
Another example that I bring is related to obsidian or volcanic glass, which is wrongly called mineral, because this material is also a rock.
In this case, the reason that obsidian doesn't fit in the definition of mineral is because this one doesn't has a molecular structure defined, so it lacks of a crystalline structure; in addition, its composition is too complex to has a definite chemical composition.
Then, we have to be careful with the use of the mineral concept, and think about origin, estructure and chemical composition of the material before call it mineral ;)
I really hope that you enjoyed this post!
PS: Another cool quote!
Geologists have a saying - rocks remember. Neil Armstrong