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Geology

Stromatolite2

This piece of a greater stromatolite formation is about the size of your fist. This face shows a cross-section through several of the rock’s layers. The layers are due to the sedimentation of minerals generated by cyanobacterial mats that used to be prevalent before larger animals evolved and began eating them. Modern day bacterial mats […]

Colloidal Crystals

A colloidal crystal is an ordered array of colloid particles, analogous to a standard crystal whose repeating subunits are atoms or molecules. A natural example of this phenomenon can be found in the gem opal, where spheres of silica assume a close-packed locally periodic structure under moderate compression.

Pyrite2

In additional to small bumps, this sample has larger scale irregularly shaped patterns. The pyrite crystal may contain larger amount of mineral elements other than iron and sulfur. Those impurities are less resistant to oxidization and corrosion from environment, and therefore form larger scale patterns.

Sand

Sand on ocean beaches is frequently a mixture of weathered rock and crushed sea shells. In the second sample to feature X-ray data from our Energy Dispersive Spectroscopy (EDS) detector you can clearly identify sand grains from silicon rich igneous rock and calcium based sea shells. Also of interest are the crystals of salt (Na […]

Pyrite

This piece of natural pyrite crystal from the Grand Teton National Park gift shop was broken to expose a fresh, clean cleavage for AFM imaging. The little bumps are iron compounds that have not been fully sulfidized. After being exposed to oxygen in the air, iron oxidized and formed little bumps because of volume increase. […]

Stromatolite

This piece of a greater stromatolite formation is about the size of your fist. This face shows a cross-section through several of the rock’s layers. The layers are due to the sedimentation of minerals generated by cyanobacterial mats that used to be prevalent before larger animals evolved and began eating them. Modern day bacterial mats […]

Pyrite3

This sample has the highest quality iron sulfide. Generally the sample is pure showing steps of crystal layers and regular crack lines between grain boundaries. There are still small bumps of iron compounds like those dominating the two previous samples. Also, there are several large, kidney-shaped patterns indicating other impurities. This sample may have been […]