When looking at the mystery material and trying to figure out whether it is a rock or a mineral there are a couple of basic things that the friend should know before jumping to conclusions. First you need to realize what a rock is and how it’s different from a mineral. If you happen to think that the material is a mineral the tests you could do to figure out which mineral it is are as follows: color (what it looks like), hardness (what scratches it), streak (the color on a porcelain plate), if its magnetic, luster (how shiny it is), cleavage (how it breaks apart), and if it reacts with HCl. Once you do all of these tests and if it comes up with a specific mineral then you know for sure it is a mineral. But if you have no definite answer on if it is a mineral then it is probably a rock. And if it is a rock then you have three different options on what type of rock it could be. It could be igneous, sedimentary, or metamorphic. It is igneous if it has then it is classified by its grain size. If it has large grains then it is intrusive and if they are not visible then it is extrusive. Also it could be felsic a lighter color or mafic a darker color. If you think that it’s sedimentary then it looks like it has layers of minerals in it. You can also do a HCL test to see if it is limestone. And finally it could be metamorphic that is categorized by foliation/banding which is light or dark layers.
Some setbacks that someone may make in trying to identify a rock form a mineral is that they may jump to conclusions too quickly such as with color size and texture. All of those things can change with different samples of the same mineral or rock so just take your time and make sure you run through all of the tests.
Great job - but a key thing to a mineral is that it is homogenous and definitie crystalline structure to it.
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