Mineral guides
Mineral Identification & Profiles
In-depth guides to the rocks, minerals, and crystals you’ll encounter in the field. Physical properties, identification tips, where to find them, and how to collect them.
In-Depth Guides
Full guides with identification tips, collecting locations, and lookalike comparisons.
Quartz
A complete guide to quartz - how to identify silicon dioxide in the field, how quartz forms, where it is found, and how to separate it from common lookalikes.
Quartz Crystals
A field guide to quartz crystals — how to identify crystal-form quartz, what good terminations look like, where quartz crystals form, and what separates crystal material from plain massive quartz.
Clear Quartz
A guide to clear quartz — how to identify colorless quartz crystals, what affects clarity, where clear quartz forms, and how collectors judge specimen quality.
Quartz Clusters
A practical guide to quartz clusters — how intergrown quartz crystals form, what makes a cluster attractive, and how they differ from single terminated points.
Loose Quartz
A field guide to loose quartz — what collectors mean by the term, how weathered free pieces differ from in-place crystal growth, and when surface quartz is still worth your time.
Double-Terminated Quartz
A practical guide to double-terminated quartz — how to recognize natural terminations at both ends, how the habit forms, and what makes these crystals so desirable to collectors.
Matrix Crystals
A guide to matrix crystals — what the term means, why many collectors value attached specimens, and how matrix changes the way a crystal is judged and prepared.
Chalcedony
A practical guide to chalcedony — how to identify cryptocrystalline quartz, how it differs from agate and jasper, and where collectors typically encounter it.
Amethyst
The purple variety of quartz, colored by trace iron and natural irradiation. One of the most popular collector minerals worldwide.
Azurite
A complete guide to azurite - how to identify it, how it forms, where it is found, common lookalikes, and what collectors should know before heading into the field.
Calcite
A complete guide to calcite - how to identify its rhombohedral cleavage, test its acid reaction, understand how it forms, and recognize where collectors find it.
Garnet
A complete guide to the garnet group - how to identify garnets, which species collectors see most often, how garnets form, and where they are found.
Pyrite
A complete guide to pyrite - how to identify it, how it forms, where it is found, and how to tell fool's gold from real gold.
Fluorite
A complete guide to fluorite - how to identify it with perfect cleavage and hardness 4, how it forms, where it is found, and how to separate it from common lookalikes.
Tourmaline
A complete guide to the tourmaline group - how to identify prismatic, striated tourmaline crystals, how tourmalines form, where they are found, and what beginners should focus on first.
Feldspar
A complete guide to the feldspar group - how to recognize feldspar in common rocks, why beginners struggle with it, how feldspars form, and what the main group-level differences mean in the field.
Agate
A complete guide to agate - how to identify this banded chalcedony variety, how agate forms in nodules and cavities, where it is found, and how to separate it from jasper and plain chalcedony.
Fire Agate
A complete guide to fire agate - how to identify it, what causes the fire, how it forms, where it is found, and what collectors should know before calling rough chalcedony true fire agate.
Peridot
A complete guide to peridot — how to identify it, where to find it, its physical properties, common lookalikes, and the best collecting locations. Arizona produces most of the world's peridot.
Turquoise
A complete guide to turquoise - how to identify it, how it forms, where it is found, what stones are confused with it, and how natural, stabilized, dyed, and imitation turquoise differ.
Aquamarine
A practical guide to aquamarine — how to identify blue beryl, where aquamarine forms, and how collectors separate it from topaz, quartz, and other pale blue lookalikes.
Diamonds
A practical guide to diamonds — how to identify natural diamond, what makes it different from quartz and Herkimer 'diamonds,' and where real diamond-bearing geology occurs.
Emerald
A practical guide to emerald — how to identify green beryl, what makes emerald different from other green minerals, where it forms, and why most natural material is included.
Fossil Coral
A practical guide to fossil coral — how to recognize coral structure in rock, how it differs from shell fossils, and where collectors commonly find it.
Franklinite
A practical guide to franklinite — how to identify this dark oxide mineral, why the New Jersey district matters so much, and how collectors separate it from other black ore minerals.
Geodes
A practical guide to geodes — what they are, how they form, where collectors find them, and how to separate real geodes from solid nodules and plain rounded rocks.
Gneiss
A practical guide to gneiss — how to identify metamorphic banding, how gneiss forms, and why it matters as field context for collectors.
Granite
A practical guide to granite — how to identify it, how granite forms, and why collectors care about it as a host rock even when they are chasing crystals rather than the granite itself.
Herkimer Diamonds
A practical guide to Herkimer diamonds — what they really are, how to identify double-terminated quartz from the Herkimer district, and why the diamond name is only a nickname.
Hiddenite
A practical guide to hiddenite — how to identify green spodumene, why the North Carolina context matters, and how to separate it from emerald, tourmaline, and other green crystals.
Jasper
A practical guide to jasper — how to identify opaque microcrystalline quartz, how it differs from chalcedony and agate, and why pattern and opacity matter so much.
Kunzite
A practical guide to kunzite — how to identify pink spodumene, where it forms, and why cleavage and fading matter so much for collectors.
Kyanite
A practical guide to kyanite — how to identify bladed kyanite, why its hardness is unusual, and where collectors commonly encounter it in metamorphic settings.
Lazulite
A practical guide to lazulite — how to identify this blue phosphate mineral, where it forms, and how to separate it from kyanite and other blue collector minerals.
Limestone Fossils
A practical guide to limestone fossils — how to recognize fossil-bearing limestone, what kinds of fossils are common in it, and how to separate it from silicified fossil material.
Morganite
A practical guide to morganite — how to identify pink beryl, where it forms, and how collectors separate it from tourmaline, kunzite, and other pink crystals.
Petrified Wood
A practical guide to petrified wood — how to recognize fossilized wood structure, how it forms, and how collectors separate it from jasper, ordinary wood, and random silicified rock.
Petoskey Stones
A practical guide to Petoskey stones — what they are, how to identify the fossil coral pattern, and why Michigan beach context matters so much for finding them.
Rutile
A practical guide to rutile — how to identify titanium dioxide in the field, where it forms, and how collectors separate it from darker prismatic lookalikes.
Schist
A practical guide to schist — how to identify schistosity, how schist forms, and why schist matters in collector geology even when it is not the main target specimen.
Thunder Eggs
A practical guide to thunder eggs — what they are, how they form in rhyolite, and how collectors separate them from classic geodes and ordinary nodules.
Topaz
A practical guide to topaz — how to identify it, why its cleavage matters so much, where topaz forms, and how collectors separate rough topaz from quartz and feldspar.
Willemite
A practical guide to willemite — how to identify it, why UV response matters, and why New Jersey is the collector context that matters most.
Zincite
A practical guide to zincite — how to identify this zinc oxide mineral, where it occurs, and why Franklin district context matters so much to collectors.
Quick Reference
Essential properties at a glance. Full guides coming soon.
Ready to find these minerals in the field?
Browse documented collecting sites with GPS coordinates and access info, or learn the field tests that make identification easy.