Point your camera at a stone and Mineralo tells you what it is likely to be — and why it thinks so, describing what it actually saw in your photograph rather than reciting a textbook.
Most stones on most beaches are nondescript, and an app that confidently names every one of them is lying to you. When a specimen has nothing diagnostic about it, Mineralo says so instead of picking the nearest match and dressing it up with a number. An identification you can trust is worth more than one that is merely fast.
Every find you keep records where you were, so your collection doubles as a map of the places you have been — and you can find your way back to the good spots. Ranks and badges mark the milestones: new species, new places, rarer material.
Rocks are outdoors, and outdoors has no signal. When the network does not answer, identification runs entirely on your iPhone.