View source for Deep sand dunes as easy source of silicon

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[[Silicon]] is nice as a building material since it is the most abundant element around on Earth. <br>
(Ignoring [[oxygen]] that can't be used on it's own to build anything.)


== Extraction effort == 

Since silicon is a non-volatile element <br>
it can't be drawn from the atmosphere like the building material <br>
carbon can be from atmospheric carbon dioxide (as done by trees). <br>

Fine sand would obviously be an easy resource not requiring hard rock mining.

== Destructiveness on life & geologic history records == 

=== Life ===

With some precautions on 
* sterile operations 
* water table preservation 
* migration path preservation 
eventually present microbial life deep down the dunes interior <br>
may be quite resilient through it's homogeneous distribution and spread over a very large volume. <br>
Actual investigations needed to confirm. <br>

=== Geology ===

Drawing carbon from air is nondestructive as <br>
atmospheres are structureless and thus in-destruct-able in the literal sense of the word. <br>
(Well, ok, the CO2 gets destructured but hat is deletion of value devoid redundant trivial information.) <br>

For silicon instead some sort of more or less geology destructive [[mining]] and [[transport]] is needed. <br>

Sand, as the choice of source, is already a quite homogeneous substance. <br>
Remnant geologic historic information only being present inside the grains. <br>
Erosion has already erased much of the origin history. <br>
And since sand is homogenized removing a part of it for chemical processing will <br>
still leave the same amount of geology history information in the remaining rest of the sand. <br>
A bit like holographic data storage as a weak analogy. <br>

== Best silicon based gemstones ==

See also: [[Silicon]]

Most silicates are "merely" around Mohs hardness 7 often below. <br>
Nothing near [[diamond]] [[lonsdaleite]] and even [[sapphire]]. <br>
Quartz itself being the defining element of Mohs 7. <br>
Crystal structures are often on the more nontrivial <br>
complex side in unit cell size or low unit cell symmetry. <br>

=== Polymorphs ===

There are very hard and unusually dense metastable high pressue modifications of pure SiO<sub>2</sub> <br>
like the tetragonal [[stishovite]] with rutile structure. <br>

=== Binary compounds ===

More thermally stable and similarly hard there are the [[silicon nitride]]s including [[nierite]]. <br>
[[Nitrogen]], while much less abundant than silicon, <br>
is obviously extremely available on Earth as the main component of our atmosphere. <br>

'''Nierite Si<sub>3</sub>N<sub>4</sub> as backup to moissanite SiC:'''

Running out of atmospheric carbon dioxide to make [[moissanite]] <br>
(as discussed on page: [[Large scale carbon sequestration in deep sand dunes]]) <br>
there is still plenty of nitrogen to make [[nierite]] <br>

A danger of depleting our atmosphere of nitrogen would, if anything, be a very long term prospect. <br>
It would be very possible though due to silicon being much more abundant than nitrogen. <br>
And bad. Not to mention the problem of all the released oxygen <br>
if not bound to some reducing element like non-oxidized iron which is hard to come by <br>
in these enormous quantities without reaching deep down into Earth. <br>

Looking at just sand dunes these are a minute part of Earth's silicates. <br>
=> Q: How much of sand dunes would be consumed when combined with all of Earths atmospheric nitrogen? <br>

== Related ==

* [[Large scale carbon sequestration in deep sand dunes]] - one possible use of silicon ins and dunes