• Marisa Acosta

Calcite Growth Experiments

In addition to being so-so-so close to resubmitting our TitaniQ manuscript, and to working on my Butte manuscript, I've been trying my chops at growing calcite. The project, designed to quantify the effect of substrate roughness on growth style and trace element incorporation, is being done by myself, recently- graduated undergraduate Molly Pickerel, and PhD candidate Ellen Olsen.

And the experiments are so fun. Definitely a welcome reprieve from the doldrums of dissertation- and manuscript-making

Below, peep some results from our trial run (we're just trying to wrinkle out potential problems before running the real experiments).

The little guys growing. The apparatus drops out calcite crystals, but we wanted seeds for this. There are three crystals attached to the glass round, each one attached differently (carbon tab, superglue, and crystal bond) to see which would work best. Carbon tab one out for holding up during the experiment and being easy to detach from after the fact. It also doesn't hurt that it's conductive, making SEM imaging a bit easier.

A reflected light image of a cleaved calcite surface, the {104} face. This is representative of the surfaces used in the trial run

A reflected light image showing overgrowth! Note the sorta vermicular fluid inclusions.

Reflected light image of the growth surface. Note the lustrous, tabular islands of overgrowth.

SEM-BSE image (BSE can be better than SE for really charge-y, topographically diverse samples like this) showing the tabular overgrowth features reflecting in the image above. Also , there's a bunch of "soccer balls" of homogeneously nucleated calcite that fell onto and adhered to the surface.

Those terraces though!

SEM-BSE image of the growth terraces. Note the lighter-grey blocks - these are halite crystals. Even though we dunked the crystals in DI water after the experiment, little bits of saltwater must have adhered to the terraces and evaporated to leave behind halite.


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