Shale Atlas Crystals

Shale Atlas Crystals is an offline reference and practice trainer for the rocks and minerals people actually pick up. Thirty common minerals and twelve common rocks, every one of them drawn by the app itself rather than photographed.

Colour is the first thing you notice about a mineral and the least reliable thing about it. Quartz runs from colourless through smoky grey to deep violet without changing a single measurable property. So this atlas is built on the properties that hold still: lustre, streak, hardness on the Mohs scale, crystal system, and the way a specimen breaks.

WHAT IS INSIDE

ATLAS
Browse thirty minerals and twelve rocks, filtered by hardness band, lustre or crystal system. Every record carries Mohs hardness, streak colour, lustre, crystal system, cleavage or fracture, typical colours and a short identification tip. Minerals are drawn as faceted solids built from their own crystal system and habit, with elongation, termination and twinning set per species. Rocks are drawn as hand samples with their real grain, layering, vesicles or foliation. A reference strip renders all seven crystal systems side by side.

KEY
A stepwise identification key that runs the four field tests in the order a geologist uses them: lustre, then streak, then hardness against everyday objects, then cleavage. The shortlist narrows in front of you at every step, and every option shows how many candidates it would leave, so what you take away is the method and not just an answer.

HARDNESS
An interactive Mohs ladder carrying the ten index minerals and the everyday references that stand in for a boxed kit: fingernail at 2.5, a copper coin at 3.5, a steel nail and window glass at 5.5, a steel file at 6.5. Load any two species onto the bench and see which scratches which, including the cases where two are simply too close to call.

IDENTIFY
Fifteen question rounds. Each question draws an unlabelled specimen and lists the properties you would have measured in the field. Choose from four species. Get one wrong and the feedback names the single property that would have settled it. Species you keep missing come round more often.

PROGRESS
Per species mastery bars, best streak, lifetime accuracy, and a round by round accuracy line drawn on a canvas.

HOW IT WORKS

Everything runs on the device. There is no internet connection of any kind, no advertising, no analytics, no accounts and no sign in. There is no sound at all: feedback is visual, with an optional short haptic buzz you can switch off in settings. Your progress is stored on the device and survives closing the app.

Every crystal is generated from its own crystal system and habit parameters, lit from one fixed direction, so a species always renders identically. Nothing is downloaded and no image files are shipped.

A NOTE ON WHAT THIS IS NOT

This is a learning aid for common specimens, not a determination service. Real samples vary, a hand specimen can be a mixture rather than a single species, and nothing here should be used to judge whether a mineral is safe to handle, safe to break or safe to keep.