Diatoms and Silica Patterns

Back when I was a kid, diatoms were "up to" filtering my mothers salt water fish tanks via this:

I was surprised to see that their cell walls are made with/from silica. I always thought that diatomaceous earth was a mild abrasive (in addition to being a fine filter).

How does hydrated silica compare to pure silica?

hydrated silica: think silica gel that has been in 100% humidity for a long while.

The physical properties are slightly different (slightly less dense, owing to the lower molecular weight of water compared to SiO₂, and a difference in infrared spectrum.)

hydrated silica gel probably will dissolve in highly concentrated caustic soda a lot quicker than dry silica gel.

There could be structural issues with depositing a thin layer of hydrated silica on a substrate, then drying it to completion (pure, dry silica), perhaps there would be issues with cracking, flaking away, peeling, but I have no data on that at this time.

I've thrown away many packets of silica gel, and have seen the contents on a few occasions, but have never paid attention to any physical properties, other than its ability to adsorb water.

In my reference to "mild abrasive" I was really referring to the Moh's scale. While quartz is 7 on that scale, I looked it up, and silica gel is 2-3, so is indeed a mild abrasive. Various sources give Moh's hardness for diatomaceous earth from as low as 1 to as high as 6. I presume that variation is due both to impurities and to differing geologic processes subsequent to deposition.

Interesting appraisal of the silica contents. I give you a GA for the research on it!

I think there must have been a reason why the Egyptians withheld straw from the Jews whom were making bricks in Egypt. Perhaps those bricks lacked integrity so they would not be approved for used in official construction for the Pharaoh?

Later on, the Jews were once again allowed to have straw for brick-making, and I suspect things improved immensely.

A little over 50 years ago I watched low-end brick-making in Chile. A horse was made to walk around outside a mud pit with a pole in the middle, dragging some form of stirring device of wood, to stir in the straw that they added.

They would pour the mixture into wooden molds, and after drying, they built a large arched oven out of the bricks (no mortar), covered that with dry dirt, and built a fire inside the oven. As I recall, they kept the fire burning for several days. Once it cooled down, they disassembled the oven, and sorted the bricks. The ones on the inside, closest to the fire, were the best ones, used for building houses. The outer ones were used for building garden walls.

Mick Jagger diatom....

Now, that is cute, but way to silly to make further comment upon.

Rice may be a terrestrial organic alternative to diatoms. About 20 percent of the husk is silica, which to some extent oxidizes with the organics when the husk is burned. Maybe a GMO rice could grow a silica-enriched husk from which the silica could be extracted through the use of a ghee-whiz organic-removal solvent process. Or, maybe, I am just grasping for (rice) straws, and all we would get is a rice pudding with a real kick.