Field guide
Rock guides & field notes
Practical explainers on identifying and understanding rocks, crystals, minerals and gemstones.
How to Identify a Rock in the Field: A Simple Checklist
You don't need a geology degree to start telling rocks apart. These five checks will get you most of the way there before you even open an app.
Understanding the Mohs Hardness Scale
Hardness is one of the most useful, least understood properties in mineral identification. Here's what the Mohs scale actually measures and how to use it.
Real or Fake? Spotting Synthetic Gemstones
Lab-created and imitation gemstones have gotten remarkably convincing. These visual habits can help you know what to look for — and when to get a second opinion.
Igneous, Sedimentary, Metamorphic: The 3 Rock Types Explained
Every rock you'll ever pick up falls into one of three families. Once you know what to look for, telling them apart in the field gets a lot easier.
Quartz vs. Calcite: How to Tell Them Apart
Quartz and calcite can look surprisingly similar at a glance, but a few quick, low-tech tests will separate them every time. Here's how.
Geodes: How to Find Them and What's Inside
A plain gray rock can hide a hollow chamber lined with crystals. Here's how geodes form, where to look for them, and how to open one without wrecking what's inside.
Is It a Meteorite? Simple Checks Before You Get Excited
Found a dark, heavy rock and wondering if it fell from space? Here are the checks real meteorite hunters use before they get their hopes up — and why a lab is still the final word.