Looking for Rock/Mineral Identification Flowchart

Question

As a christmas present, I bought a box of minerals/rocks for my girlfriend, who recently got interested in geology. Unfortunately, she could not attend the identification class in university. The box contains:

unakite
snowflake obsidian
red jasper
rose quartz
rock crystal (quartz)
tiger's eye
amethyst
sodalite
magnesite
agate
aventurine (green)
calcite

I have found some identification flowcharts such as

But that is missing, among others, magnesite, the various quartz variations and obviously doesn't contain the non-minerals.

I'd like to put together a flow chart so she can identify all those materials. How would one go to identify those rocks and minerals, in a flow-charty-manner?

Answer 1

From my own experience of being a geologist for close to fifteen years, flow charts like that are of very limited use. The truth that you probably did not want to hear, is that it takes years of experience and education to learn how to identify minerals.

For example, olivine is defined in your chart as "no streak, cannot be scratched, green, grainy". I know of many other minerals which are exactly like that (epidote is one example). I also know of olivine which doesn't satisfy these conditions - not all of them are "grainy" (whatever that even means?).

You can write a custom flowchart for the minerals in that specific box, but that would be rather boring because most of them are just silica in various forms. Anything more complex than that would lead to false positives and false negatives for anything that slightly deviates from the rubric (which is almost everything).