"Greenlandic Margarosanite" - Tugtupite Extreme, CRACK THAT ROCK!!!

Contributed by: Mark Cole
Date: Apr 11th, 2026
Locality: Taseq Slope, Ilímaussaq complex, Kujalleq, Greenland (See on Mindat)
Size: 3 x 2 x 5.5 inches
Weight: 2.43 lb

Description:
My mantra on the Facebook Fluorescent Mineral Group is "Crack that rock!". Folks new to the hobby are sometimes used to finding a rock that is just beautiful in its natural state and would never think of taking a hammer to it. Fluorescent rocks often require just that. You might find a specimen that has an interesting fluorescence and want to just leave it like that. But what folks often do not realize is that weathering - exposure to acid rain, sunlight, etc. can weaken fluorescence on the surface over the eons. Crack it open and you never know what you might find!

This is an excellent example. The first picture shows the rock "in whole", white light and SW UV. It\'s a respectable chunk of analcime (fluorescent blue) with a little red tugtupite and maybe a hint of chkalovite. But I had a feeling there was more inside, so I stuck it in the rock splitter and minutes later I had two halves which fit perfectly with each other, offering mirror images of the inside.

And oh, what an inside! The vibrant red fluorescence is tugtupite encircling a beautiful pearly white fluorescence from a very special variety of chkalovite (named "Greenlandic Margarosanite" by one of the Geo-Tour members). Bright eyes of blue/white analcime balance out the assemblage for a truly rich and spectacular specimen. Under midwave the chkalovite takes on an unusual yellow/green fluorescence and under longwave the tugtupite shows off its salmon fluorescence.

Moral of the story? Look inside, crack it - you never know....

Originally posted by Mark Cole on Nature's Rainbows in 2017.