diatomite - teaching hand specimen of lacustrine diatomite
Diatomite or diatomaceous earth is a sedimentary rock composed of the siliceous cage-like shells of diatoms, single-celled algae that live in the shallow water of lakes and the sea. As they die there is a constant rain of their shells onto the seabed and lake bottoms, where they accumulate to form chalk-like diatomite. The shells of diatoms are made of opal, so unlike calcareous chalk, diatomite will not effervesce with a drop of hydrochloric acid.
Diatoms extract the silica of their shells from the water they live in. It takes special conditions to form a deposit of pure diatomite - active volcanism makes silica available, while very cold water inhibits the growth of foraminifera, the plankton with shells composed of calcium carbonate. Diatomite forms in high elevation lakes and in polar seas, and is found where similar conditions existed in the past. This lacustrine diatomite is from Mineral County, Nevada.
Diatomite has industrial uses in filtration, in insulation and cat litter, as a filler in rubber, paint, cosmetics and plastics, as a mechanical insecticide and as a stabilizer in dynamite. It is also used as a polishing agent in toothpaste and as a component of some cement blends.
These specimens ship first class unless combined with other purchases.
Select a specimen: You can select a specimen by telling us what is in the photo with it, a blue or black and silver pen, a black mechanical pencil or one of those plus some number of coins, or you can let us make the selection.
Making multiple purchases? Click on the "combine shipping" button in the shopping cart. We'll send an invoice with combined shipping. A link in that invoice will bring you back to checkout, no hassle.