Flashcards
Tap a card to flip. Toggle any property; switch on Test me to blank the names and identify from the specimen alone. Use 🔀 on a card to pull a different photo of the same species.
Name-That-Rough
Four strongest clues first — cleavage, surface marks, crystal system and colour, in a fresh shuffled order every round — then everything else. Guess early for more points. Build a streak.
The Rough Detective
Work it exactly like a gemologist holding the stone: crystal system first, then heft and lustre, then cleavage and surface marking, then colour — and anything left over after that. Each answer narrows the field. Unsure of one? Skip it and keep going.
How Rough Grows
Every clue on the bench is a fossil of how the crystal grew. Read the growth story and the shape reads itself.
A crystal is a lattice given room to repeat. When atoms are free to stack into open space — a vug, a fracture, a gas pocket — they build flat faces at angles fixed by that lattice. Those angles are the crystal system, which is why external form is the first thing you read on rough. Give quartz a cavity and it grows a six-sided prism capped by a rhombohedral point, every time.
Grown crowded, crystals can't finish their faces — these are anhedral grains. Grown free into open space they become euhedral, sharp and diagnostic. The champion of open-space growth is the geode.
Anatomy of a geode
Mineral-rich water seeps into a cavity and deposits inward, layer by layer, over thousands to millions of years. Crystals point toward the hollow centre — the empty core is proof the water ran out before it filled.
Growth marks you'll read on the rough
Each feature is a growth event frozen on the surface — and each narrows the field fast.
The Seven Crystal Systems
Symmetry sets everything downstream — the forms a crystal can take and how light behaves inside it. Isotropic (cubic) stones never double or show pleochroism; uniaxial and biaxial stones do.