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Mohs Hardness Scale Training Center

Ari Raider's Training Materials · Treasure Mountain · Training Center 5 of 6

The Mohs Hardness Scale

The Copper Cathedral is sagging because something soft was holding it up. Hardness — who scratches whom — decides which pillars can take the weight.

What you're training for

In the Copper Cathedral, the soft metal has been prised out of the pillars and the roof is starting to sag. Ordering minerals from softest to hardest is what tells the team which pillars still hold. Train here first; prove it in the simulation.

The science

  • The Mohs scale runs 1 (talc) to 10 (diamond). A mineral scratches everything softer than itself.
  • Everyday testers: a fingernail is about 2.5, a copper coin about 3, a steel nail about 5.5, glass about 5.5.
  • Copper sits at 3 — soft for a metal. That's why copper jewelry wears smooth, and why the Cathedral's pillars are a problem.
  • Quartz at 7 beats a steel nail — which is why beach sand (mostly quartz) can scratch glass.

Teach it today — no prep

The Scratch Lab. Fingernail, penny, steel nail — in that order — against whatever specimens your room owns. Rank them by what scratched them, then check the ranking against a Mohs chart. One rule keeps it civilised: scratch the rock, never the furniture.

Trained and ready? Prove it at Stop 5 — the Copper Cathedral. Free, no logins, progress saved on the device.

Enter the Realm at Stop 5

Resources in this training center

Worksheets, reading passages, flashcards and printables for this lesson are being added — new resources land here first. Get one email a month when they do, or browse the whole free library.

The hands-on half: the Treasure Mountain Adventure Kit puts six real specimens, six Digs, six Gemlings and the Realm map in your students' hands — $19.99, or $15 a student for classrooms.

More Treasure Mountain training

Rock Families · Rock Layers · Rock Cycle · Mineral Properties · Mohs Hardness · Crystals & Glow · Enter the Adventure →

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