ROCKHOUNDRY
Read the stone — minerals, crystals, and the rockhound's field craft.
From estimating a specimen’s Mohs hardness and calculating its specific gravity to classifying a crystal system, planning a tumbling schedule, matching a UV fluorescence color, and estimating a specimen’s weight, RockHoundry pairs free field-craft calculators with practical guides and a richly illustrated museum. Read the stone.
Rockhounding Calculators
Free tools for the field and the workbench — Mohs hardness estimator, specific gravity calculator, crystal system identifier, tumbling grit schedule calculator, UV fluorescence guide, and specimen weight & size estimator.
Mohs Hardness Estimator
Narrow a specimen's hardness to a Mohs range from field scratch tests against a fingernail, a penny, glass, and a steel file.
Specific Gravity Calculator
Turn a weight-in-air and weight-in-water reading into a specific gravity figure and a density band.
Crystal System Identifier
Classify a unit cell's edge lengths and angles into one of the seven crystal systems.
Tumbling Grit Schedule Calculator
Build a coarse-to-polish grit schedule sized to your rock's hardness and tumbler type.
UV Fluorescence Guide
Match a specimen's longwave or shortwave UV glow against commonly fluorescent minerals.
Specimen Weight & Size Estimator
Estimate a rough specimen's weight from its dimensions and a mineral's specific gravity.
Museum of Minerals
Wander an immersive, richly illustrated collection — minerals and crystals, gemstone rough, the agate and quartz family, and fossils and specimens, each in its own gallery. Every entry, image, and fact is drawn from Wikipedia and Wikimedia Commons.
Tour the museum →From the Journal
Practical guides on mineral identification, field testing, crystal systems, rock tumbling, and building a rockhounding field kit — reading to pair with the calculators above.
How to Identify a Mineral in the Field: A Beginner's Testing Method
A step-by-step field identification routine — color, streak, luster, hardness, cleavage, and specific gravity — for narrowing down an unlabeled specimen without a lab.
The Mohs Hardness Scale Explained: The Ten Reference Minerals
What the Mohs scale actually measures, why it's ordinal rather than linear, and how the ten index minerals from talc to diamond translate to a field scratch-test kit.
Specific Gravity Testing at Home: The Hydrostatic Weighing Method
How to measure a mineral specimen's specific gravity with a kitchen scale, a container of water, and a length of thread — and what the resulting number actually tells you.
The Seven Crystal Systems: A Rockhound's Guide to Crystal Symmetry
A plain-language walkthrough of the seven crystal systems — cubic through triclinic — what actually defines each one, and how to recognize the difference between system and habit.
Rock Tumbling for Beginners: Grit Stages Explained
Why rock tumbling uses four separate grit stages instead of one, what each stage actually does, and how to avoid the most common first-batch mistakes.
UV Lamps for Rockhounding: What Longwave and Shortwave Actually Show You
Why some minerals glow under ultraviolet light, the practical difference between longwave and shortwave lamps, and how to run a fluorescence test properly.
Keep Learning
Plain-language explainers on the building blocks of mineralogy — how crystals form and are classified, the tests that narrow down an identification, the fluorescent minerals collectors chase, and how rockhounding finds turn into a tumbled or displayed collection.
Visit the Learn hub →