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Iron, Light, and the Many Shades of Schorl: Rea...
Schorl tourmaline color explained through iron chromophores, oxidation state, site occupancy, pleochroism, and the limits of what spectroscopy and chemical analysis can establish.
Iron, Light, and the Many Shades of Schorl: Rea...
Schorl tourmaline color explained through iron chromophores, oxidation state, site occupancy, pleochroism, and the limits of what spectroscopy and chemical analysis can establish.
When a Spinel Looks Two-Faced: Pleochroism, Pol...
Why does cubic synthetic spinel sometimes show pleochroism and birefringence? Explore how flame-fusion growth and cooling create strain fields that distort an isotropic lattice.
When a Spinel Looks Two-Faced: Pleochroism, Pol...
Why does cubic synthetic spinel sometimes show pleochroism and birefringence? Explore how flame-fusion growth and cooling create strain fields that distort an isotropic lattice.
When Light Enters a Glass-Ceramic: How Surface ...
How surface roughness, refractive-index contrast, and crystalline microstructure control translucency in glass-ceramic gem materials, and why appearance alone cannot confirm composition or treatment.
When Light Enters a Glass-Ceramic: How Surface ...
How surface roughness, refractive-index contrast, and crystalline microstructure control translucency in glass-ceramic gem materials, and why appearance alone cannot confirm composition or treatment.
When One Tourmaline Crystal Is Not One Sample: ...
Why one tourmaline crystal can defeat a single measurement: liddicoatite zoning, spectroscopic sampling limits, reference dependence, and the evidence needed before extending a local result to a whole gem.
When One Tourmaline Crystal Is Not One Sample: ...
Why one tourmaline crystal can defeat a single measurement: liddicoatite zoning, spectroscopic sampling limits, reference dependence, and the evidence needed before extending a local result to a whole gem.
Andalusite’s Pleochroism: Why One Crystal Can S...
Why andalusite shows different colors depending on viewing direction: anisotropy, biaxial optics, iron absorption, polarization testing, and the limits of a pleochroic observation.
Andalusite’s Pleochroism: Why One Crystal Can S...
Why andalusite shows different colors depending on viewing direction: anisotropy, biaxial optics, iron absorption, polarization testing, and the limits of a pleochroic observation.
Star Sapphire in Placer Deposits: Reading Weath...
How weathering and placer processes concentrate corundum, and why star sapphire asterism comes from oriented rutile inclusions and cutting orientation rather than from river transport.
Star Sapphire in Placer Deposits: Reading Weath...
How weathering and placer processes concentrate corundum, and why star sapphire asterism comes from oriented rutile inclusions and cutting orientation rather than from river transport.