Decorating with Minerals & Fossils

 In Ammolite

Alberta (OR SASKATCHEWAN), Canada

Baculites inhabited marine environments during the late cretaceous period, from 99 to 65 million years ago, and are closely related the more commonly seen ammonites which lived during the same period.  Unlike ammonites with their distinctly coiled shells, baculites were elongated and similar in appearance to modern day squids—the main difference beaing that their bodies were contained in shells.

Baculites are thought to have been typically oriented vertically in life, and swam in shoals inhabiting the middle depths of an ocean that borders the present day location of the Rocky Mountains, particularly in the area of Alberta, Saskatchewan, and Montana.

The beautiful iridescent material accenting the fossil is known as ammolite, a sub-millimetric layer composed primarily of aragonite, though which may also contain trace amounts of silica, pyrite, and calcite.  The iridescent results from interference between light waves reflecting off the stacks of nanoscale aragonite platelets that comprise the ammolite layer.  As the different stacks of platelets have different thicknesses, rebounding light waves are out of phase and experience interference—a more common example is the iridescence of CD’s caused by the same phenomenon acting on the laser etched surfaces of a silicon disc.


bacculite

This beautiful section of baculite measures 29 x 8 x 3cm and is displayed on a custom stand.  The section is remarkably complete and the ammolite layer is largely free of the typically seen fracturing.  Moreover, the iridescent of the baculite is highlighted by the uneven surfaces of the grooved shell, which also add a degree of three-dimensionality to the piece.

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