A Polished End Cut Slab Showing Uranium Alteration in Motion

Some uranium minerals shout. Others explain.

Small slabs often carry more information than large specimens. This polished end cut gummite slab from Ruggles Mine proves that point immediately. It is not large, not flashy at first glance, and does not rely on size to make its case. What it does show is uranium alteration frozen in place, with color, structure, fluorescence, and radiation behavior all visible in a single cut surface.

This piece is a teaching slab. It shows how uranium moves, oxidizes, hydrates, and concentrates as primary minerals break down. You can see the chemistry at work through the rock.

The Locality: Ruggles Mine, New Hampshire

Ruggles Mine is one of the most famous mineral localities in New Hampshire. Located in Grafton, it is best known for its complex pegmatites, feldspar, quartz, mica, and a long list of secondary minerals formed through fluid movement and alteration.

Uranium minerals at Ruggles are not the headline attraction, but they are quietly excellent. The pegmatite system provided pathways for uranium to migrate and concentrate, producing gummite as a secondary alteration product rather than a primary ore.

After years of limited access, Ruggles Mine has recently reopened to collectors. That reopening matters. It gives new context to older material like this slab and allows collectors to revisit classic New England pegmatites with modern tools and a better understanding.

What This Slab Actually Is

This is a polished end cut slab. The cut exposes the internal structure cleanly while preserving the natural alteration textures. The surface shows bands and patches of yellow, orange, and darker material that trace uranium migration pathways.

Gummite is not a single mineral. It is a group term for hydrated uranium oxides and silicates that form when primary uranium minerals break down. In this slab, the gummite developed along fractures and planes where fluids moved through the pegmatite.

Polishing the surface does not hide that story. It sharpens it.

UV Fluorescence: Where the Chemistry Lights Up

Under shortwave UV, the slab changes completely. Bright green fluorescence erupts along altered zones, especially near the lower portion of the slab. This glow comes from uranyl ions excited by ultraviolet light.

The fluorescence is not uniform, and that is the point. It maps uranium concentration and oxidation state directly onto the slab surface. Areas with stronger glow indicate more active secondary uranium phases.

This alteration is apparent; discuss without guessing.

Radiation Behavior and Spectrum

Using the same controlled geometry used throughout this series, the slab returned a stable reading in the low to mid 400 CPS range during a 20-minute acquisition.

The spectrum is dominated by thorium-chain features rather than a pure uranium-ore signature. That aligns with what Ruggles' material should show. Uranium is present, active, and mobile, but it is not locked into dense primary UO2.

This spectrum matches the visual story. Alteration lowers total intensity while increasing surface response and fluorescence.

Why End Cut Slabs Matter

Calling this an end cut matters. This is not a decorative polish job. It is a cut meant to expose structure, chemistry, and texture without overworking the material.

End cuts allow collectors and researchers to:

• See uranium migration pathways

• Map fluorescence zones accurately

• Compare spectra to visible alteration

• Preserve fragile secondary minerals

This slab does all of that while remaining stable and displayable.

How This Fits Into My Hot Box

In my Hot Box, this slab sits near altered uranium specimens rather than primary ores. It plays a different role. It teaches movement instead of mass.

Where dense uraninite demands respect through raw output, this gummite slab earns attention through behavior. It glows, responds, and tells you exactly where the uranium went and why.

It is a quiet specimen with loud science.

Why Ruggles Gummite Is Worth Studying

Ruggles Mine gummite is underrated. It lacks the fame of Western uranium districts, but it offers something just as valuable, an apparent alteration in a controlled geological system.

This slab shows:

• Uranium mobility in pegmatites

• Secondary mineral formation pathways

• Strong uranyl fluorescence

• Moderate CPS with clear spectral structure

For collectors who care about process rather than just numbers, this is excellent material.

Up Next

Next, I will be looking at Zippeite on Uraninite from the Blue Lizard Mine.

That piece represents a later stage of uranium alteration and further extends fluorescence and chemistry. Where this Ruggles gummite shows the early to middle stages of uranium breakdown, zippeite shows what happens when alteration goes all the way.

Bright, fragile, and chemically expressive, it will make a perfect follow-up.

If pieces like this interest you, RadioactiveRock.com carries uranium minerals that follow the same documentation workflow used here. Every specimen is tested, photographed, and measured with repeatable geometry so collectors can make informed decisions.

Feel free to explore the shop, or reach out if you want to compare spectra or discussan apparent mineral behavior. That conversation is half the fun.

Stay curious, stay safe, and keep your detectors chirping.