Dinosaur Fossil Gembone Slab on Maple Burl Display

As usual, being cooped up at home (virus avoidance) has me looking for things to photograph. I haven’t acquired any antique cameras in 2021, but hopefully will find something, so I decided to look at our other collections.

In past posts, I commented about having a small collection of fossil dinosaur bones and shared two items; a rare 100% pyritized ichthyosaurus vertebrae and a pliosaur humerus bone with pyrite displacement.

For this post, I thought it would be fun to show something new on Show & Tell, a high-quality dino gembone. This is a 7.5-inch-wide polished slab displayed on a maple burl stand. We acquired it from a dino bone expert (friend) years ago. He also made the wood display. The color range and vividness are outstanding.

As background, the majority of fossil dino bones have a ruddy brown color. Agatized bone is the next level and the cells start looking like tiny agates. The most sought-after specimens have colorful agatized cells. If the fossilization process creates especially vivid colors, collectors use the term “gembone." The best examples have colors with lots of clarity and depth and display a gemlike appearance.

Most specimens are dominantly one color (i.e. reds and oranges) while others display a surprisingly large range of colors (i.e. reds, oranges, blues, mauves, yellows, purples and so forth). There are also examples in which individual cells display “chromatography;" when different colors and patterns appear in the banding. And as with most collectables, dino gembone can become addicting.

This particular slab of gembone has a variety of vivid colors with some of the cells displaying chromatography. To capture the truest colors, I photographed the specimen using “daylight” color-balanced soft-boxes. If you looked at this same piece under normal light bulbs (incandescents), the colors are dull.