Name 2 tests you can determine what minerals a rock is made of?

Answer 1

While a precise mineralogy of a rock can be determined via optical petrography or X-ray Defractometry (XRD). two simple test that you can perform in a classroom lab are acid tests and scratch tests.

Different minerals will dissolve in different acids. before the advent of spectrometry, many geologist would painstakingly dissolve rocks one mineral at a time to estimate their relative abundances.  Dilute hydrochloric acid, or sometimes even vinegar, can cause certain carbonate baring rocks to bubble or fizz. This would imply the presence of Calcite, a calcium carbonate mineral, found commonly in schools in the form of chalk

Different minerals will also have different hardnesses. while this is rarely completely diagonal, this difference does help to narrow down possible minerals in a rock. if you can scratch a rock with just your fingernail, it is much softer than a rock that can scratch metal or glass. rocks hardnesses are classified on the Mohs scale from 1 to 10, 1 being the softest, might be talc (the source of talcum powder) while a 10, the hardest, might be a diamond. The are numerous kits available, including sample minerals and scratch plates, in order to test and compare a minerals hardness.

For example, if you found a white clear crystal, it might be difficult to tell just by looking at it if it were calcite or quartz. However if you could scratch it with something made of steel, like a nail. you would know that it has to have a hardness of less than 4. quartz has a hardness of 7, while calcite has a hardness of 3. If you had to pick between the two, calcite is probably the answer, and you could further test it by seeing if a drop of dilute acid makes it bubble.