Dravberg Rocks

Most people who pick up an interesting stone put it on a windowsill and never find out what it was. Dravberg Rocks is for the mildly curious: enough of a field guide to settle the question, not so much that it becomes homework.

Twenty-eight minerals and rocks are described the way you would actually meet them — quartz in a riverbed, pyrite weathering out of shale, the rusty crust of goethite over anything containing iron. Each entry gives hardness on the Mohs scale, lustre, streak colour, crystal system and where to look, along with a paragraph about what makes it recognisable in the hand rather than under a microscope.

▸ Inside

– Field Guide — all twenty-eight entries, searchable by name, group or crystal system
– Identify — a three-question key: how hard, what lustre, what streak
– Collection — log the specimens you actually pick up, with place and a field note
– Glossary — sixteen terms a field guide keeps using and rarely explains

▸ How the key works

You answer only what you can see. Leave the rest on Any. Hardness is a rough band rather than a number, because in the field it is: a fingernail marks up to about 2.5, a copper coin to 3.5, a steel blade to about 5.5. Lustre is how a fresh break handles light. Streak is the colour of the powder, which is far steadier than the colour of the lump. Three answers usually cut twenty-eight down to two or three candidates, and the entries tell you how to separate those.

▸ The collection

The tray is yours. Add a name, where you found it, and whatever you noticed at the time — the note is the part you will be glad of in a year. Nothing is uploaded anywhere, because there is nowhere for it to go: the app declares no internet permission at all.

It is not a mineralogy textbook and does not pretend to be. It is the thing you check before the stone goes on the windowsill.

Works without internet.