Table of Contents

• From the Editor: Musings from a Dyed-in-the-Wool Fluoresophile by Howie Green 1–3
• The Spinel Paradox, A Mineralogical Thriller by Ludo Van Goethem 4–8
• The Color Blue by Cynthia L. M. Brown 9–14
• Rayleigh Scattering by Justin Bank 13
• Field Trip Report: Penn/MD Materials Quarry, Lancaster County, PA by James A. Van Fleet 15–16
• Fluorescent Mineral Specimen Gallery by — 17
• UV Systems, Inc. Special End of Year Sale by UV Systems, Inc. 18
• Sustaining Member Notice by — 18

From the Editor: Musings from a Dyed-in-the-Wool Fluoresophile

By Howie Green · pp. 1–3

Blue is the focus of this editor’s column, which connects the author’s memories of the blue-painted city of Tzfat in Israel with Kabbalistic symbolism and the history of blue dyes. It examines uncertainty around the Biblical Hebrew term tekhélet, including evidence for a dye made from sea-snail secretions that sunlight could shift toward blue. The column also explains indigo dyeing and closes with photographs of blue-fluorescing mineral specimens.

The Spinel Paradox, A Mineralogical Thriller

By Ludo Van Goethem · pp. 4–8

A lazurite specimen from Afghanistan presents an apparent spinel signal despite white epitaxial crystals that optical tests and SEM/EDX identify mainly as phlogopite. The investigation compares fluorescence spectra, refractive indices, density, microscopy, and chemical analyses to distinguish lazurite, afghanite-like material, forsterite, phlogopite, and a pink mixture of phlogopite and diopside. A second specimen confirms chromium-bearing spinel inclusions associated with a mixed sodalite-group phase, illustrating why fluorescence and color alone can mislead mineral identification.

The Color Blue

By Cynthia L. M. Brown · pp. 9–14

The history and science of blue pigments range from the emergence of color terms in language to the manufacture of ancient and modern materials. The article surveys Egyptian faience and Egyptian blue, lapis lazuli and ultramarine, Chinese Han blue, Maya blue made from indigo and palygorskite, and later pigments including Prussian blue, cobalt blue, cerulean, and YInMn blue. It also considers pigment chemistry, cultural meaning, and the methods scientists use to identify traces of color on historic objects.

Rayleigh Scattering

By Justin Bank · p. 13

Rayleigh scattering explains why the daytime sky appears blue and sunsets appear red. When visible light interacts with particles much smaller than its wavelength, shorter wavelengths scatter more strongly than longer ones; the article relates this effect to the composition of the atmosphere and the changing path length of sunlight at dusk. It also applies the same explanation to blue eyes and opalescent glass, where scattered blue light and transmitted longer wavelengths produce the observed colors.

Field Trip Report: Penn/MD Materials Quarry, Lancaster County, PA

By James A. Van Fleet · pp. 15–16

A Friends of Mineralogy field trip visits the Penn/MD Materials quarry in the State Line Serpentinite District of Pennsylvania, where quarrying exposes ultramafic rocks and varied mineral coatings. Collectors examine brucite on boulders at the fourth level, antigorite and talc on serpentinite at the third level, and magnesite with possible hydromagnesite on the second level. The report gives geological and collecting context, notes that lower quarry levels are underwater, and summarizes mineral identification work using SEM/EDS and powder X-ray diffraction.

Fluorescent Mineral Specimen Gallery

p. 17

This photo gallery presents fluorescent mineral specimens with captions identifying species, localities, and illumination conditions. Examples include prehnite and calcite from Tanzania, quartz with petroleum inclusions from Pakistan, smithsonite and willemite from Arizona, hardystonite with calcite and willemite from New Jersey, gypsum from Poland, and scheelite from South Korea. The captions also document specimens from Mexico, Pakistan, and California, providing locality information alongside short-, medium-, or long-wave imaging notes.

UV Systems, Inc. Special End of Year Sale

By UV Systems, Inc. · p. 18

UV Systems advertises a limited end-of-year sale on SuperBright 3 ultraviolet lights and accessories for paid-up Fluorescent Mineral Society members. The listed offers include a short-wave model 4254 for $498, a medium-wave model 4312 for $542, and a B3 battery pack for $192, each at a stated discount from its regular price. The sale runs from October 1 through December 31, 2020, with shipping and handling extra and a limit of one of each item per customer.

Sustaining Member Notice

p. 18

A page headed “Sustaining Member Notice” presents a collection of fluorescent mineral specimen photographs with captions. The specimens include youngite from Wyoming, creedite from China, hanksite from California, adularia with spodumene from Pakistan, baratovite with microcline from Tajikistan, and mellite from Hungary. Captions provide localities, specimen dimensions, and illumination conditions. This illustrated notice is distinct from the sustaining-member roster printed in the issue’s administrative back matter.