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Now, in this world I'm creating, dragons have larvae, called wyrms. There is a specific species of dragon, Spelunca meliusculus, or the superior dragon, that dwells in a special cavern. There is a high concentration of silicon in the cave vegetation they live off of due to various large opal deposits around the cavern. Their larvae are unique in that instead of having smooth skin or chitin armor, they instead have keratin armor. Once they pupate, the wyrms use the silicon in their bodies to opalize the keratin as well as some of the scales and feathers, and the result? A very pretty dragon. However, is this possible and/or viable? That is, can the wyrm replicate the conditions needed for opalization, and would opal be more preferable than keratin?

BTW, here's a link to my chatroom if you're interested in the world.

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  • $\begingroup$ Opal is harder than keratin, but also quite brittle. For all practical purposes, think ordinary glass; both opal and ordinary window glass are amorphous form of silica with similar physical properties, with the difference in appearance being due to opal containing a few percent of structural water, whereas glass has none. (To get in intuitive idea of opal vs. keratin, think window glass vs. finger nails. Finger nails don't shatter easily, but are soft; a shard of glass can scratch a finger nail, but will also shatter on impact against a hard object.) $\endgroup$
    – AlexP
    Mar 30, 2021 at 20:03
  • $\begingroup$ @AlexP The brittleness was to be expected, however, I am happy to know that it's harder. $\endgroup$ Mar 30, 2021 at 20:09

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They could not retroactively opalize scales or feathers that already protude - any location to be opalized would need to closely hug living tissues. Take teeth as an example - the glassy parts of the enamel are deposits produced during the time the tooth spent completely surrounded by gum tissues. The (hard, but not hard-as glass) dentin is produced from within the tooth, but there is living tissue there, the 'root'.

Similarly, the mineral that makes up pearls is laid down at the interface of living tissues with the kernel of the pearl, thus producing concentric layers.

As soon as there is an unbroken layer of opal, the biologic processes are confined to one side of it - but remember that nature excels in fractal strucures, i.e that the lining tissues producing the opal might branch out, even in the microscopic realm, so the effect would look like a gradual whole-scale (hah) opalization of a part macroscopically, while in truth the generating structure would look like a christmas tree. A proto-opal scale or feather or claw thus infused with living tissue would be very soft, and non-functional, so the hatchlings would not be able to use them to fly or defend themselves but that is just as it goes with normal claws, feathers, etc. My point being that you cannot have a functional (hard, thick) scale that then, retroactively, becomes opal (with, say, the scratches of a plot-relevant fight still visible) - but you'd rather have one set of functional normal scales, while the next layer of scales is opalized in the skin below.

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    $\begingroup$ Nacre is probably far easier to produce, and is based on calcium carbonate. Silicon isn't much used in biochemistry, though it has trace roles. en.wikipedia.org/wiki/Silicon#Biological_role But if there's a reason to have it, biochemistry can almost certainly make it. $\endgroup$
    – Anon
    May 6, 2021 at 6:57

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