October 06, 2026
How Geological Age Is Estimated on Mineral and Fossil Listings
Understand what an approximate geological age on a specimen listing actually means and why it usually refers to the host formation or mineralizing event.
THE FIELD JOURNAL
Mineral & Lapidary Guides
October 06, 2026
Why Locality Matters in Mineral Collecting
Learn why mine, district and regional locality can affect mineral identification, collector interest, rarity and value.
October 06, 2026
How to Buy One-of-a-Kind Mineral Specimens Online
A practical guide to evaluating exact-piece mineral listings online, from photography and condition to locality, weight and provenance.
October 06, 2026
Crystal Habits Explained: Cubes, Prisms, Rhombohedra, Clusters & More
A visual collecting guide to common crystal habits using fluorite, quartz, calcite and tourmaline examples from The Hidden Bazaar.
October 06, 2026
What Is a Matrix Specimen? Why the Host Rock Matters to Collectors
A collector guide to matrix specimens and why keeping crystals attached to host rock can preserve geological context and visual appeal.
October 06, 2026
Green Fluorite vs Purple Fluorite: Color, Habit & Collector Differences
Compare green and purple fluorite using real Mexican specimens and learn which features matter more than color alone.
October 06, 2026
Purple Fluorite Cubes: Why Fluorite Naturally Forms Geometric Crystals
Learn why fluorite forms cubic crystals and what collectors look for in purple fluorite specimens, using a Mexican example.
October 06, 2026
Tourmaline in Quartz: Why Matrix Specimens Tell More of the Geological Story
Learn why tourmaline in quartz matrix can be more informative than loose crystals, using Brazilian and California specimens as examples.
October 06, 2026
Quartz with Hematite: Metallic Iron-Oxide Associations Explained
A collector guide to quartz and hematite associations, including metallic specular hematite on a Brazilian quartz specimen.
October 06, 2026
Chlorite Phantom Quartz: How Inclusions Record Crystal Growth
Learn how chlorite phantom quartz forms and what collectors look for, using a 15 oz Brazilian cluster from The Hidden Bazaar.
October 06, 2026
Agate with Druzy Quartz: Banded Chalcedony, Crystal Cavities & Display Value
A specimen guide to polished agate with druzy quartz, using a large 76.1 oz banded agate slice from The Hidden Bazaar.
October 06, 2026
Botryoidal Goethite: What the Rounded Iron-Oxide Texture Means
Learn what botryoidal goethite is and how calcite and fluorite can grow over its rounded iron-rich surfaces.