Rockhounding Calculators & Tools
Free, practical tools for the field and the workbench — estimate hardness, measure specific gravity, classify a crystal system, plan a tumbling schedule, match a UV fluorescence color, and estimate a specimen’s weight.
Mohs Hardness Estimator
Narrow a specimen's hardness down to a Mohs range from field scratch tests against a fingernail, a penny, glass, and a steel file, plus the index minerals in that range.
Specific Gravity Calculator
Turn a weight-in-air and weight-in-water reading into a specific gravity figure and a density band using the hydrostatic (Archimedes) method.
Crystal System Identifier
Classify a unit cell's edge lengths and angles into one of the seven crystal systems — cubic, tetragonal, orthorhombic, hexagonal, trigonal, monoclinic, or triclinic.
Tumbling Grit Schedule Calculator
Build a coarse-to-polish grit schedule sized to your rock's hardness and whether you're running a rotary barrel or a vibratory bowl tumbler.
UV Fluorescence Guide
Match the color a specimen glows under longwave or shortwave UV against a curated list of commonly fluorescent minerals.
Specimen Weight & Size Estimator
Estimate a rough specimen's weight from its measured dimensions and a mineral's specific gravity before you have it on a scale.