Rocks
36 specimens across the three rock families. Tap any card for grain size, mineralogy, formation environment, and field-recognition tips.
Minerals
60 of the most common minerals. Mohs hardness, formula, streak, luster and crystal system — eight rock-formers shaded brighter.
Mohs Hardness Lab
Set a target mineral, then test it against reference minerals and household items. Mohs is ordinal: a 9 (corundum) is far harder than a 4 (fluorite), not 9/4 as much.
Pick a target mineral:
The Rock Cycle
Click any node or arrow to learn the process that drives the transition. Rocks of any family can become any other given enough time.
Tap a node or arrow to read about that part of the cycle.
Identification Key
Answer a few field-style questions and the key narrows down to the most likely rocks.
Drill
Four modes — family, hardness range, formation environment, mineral identify by properties.
0
Score
0
Streak
0
Best
—
%
Mystery Specimen
Three progressive clues. Guess at any time.
0
Solved
0
Played
—
Avg clues
Mystery #1
Daily Challenge
Eight questions. One set per day, the same for everyone. New set at midnight local time.
Today's set
Question 1 / 8