useless and misleading description and intro page clearly misleads. there is no study guide or glossary. the videos are semi useful well at least the 30min or so in total time. they were designed for kids. I wouldn't recommend this app for anyone who is looking for more than 1st graders view of rocks, gems, and minerals.
Gems metals minerals set of video Clips no longer able to play. Very good resource No longer available. ANOTHER FLOP
Mineralogy, Petrology, Geochemistry, Crystallography, Gemstones, Geology toolkit