So, why do we still get interference effects though the
stylet thickness is very, very thin? First of all the existence of an interference effect
indicates that the stylet material is double refractive. And, in order to show
an effect at all at this low thickness it must be strongly refractive.
When looking at the mineralogical tables we find that e.g. quartz is very weakly refractive
(0,009), apatite as the main constituent of human teeth as well (0,003) but calcite
- according to the literature: the stylet material! - is one of the few "kings" of
double refraction (0,172).
So, even at very low thickness calcite is able to show the first interference colour (white-grey),
and in thicker layers at the stylet root the next interference colour, which is yellow.
In a nutshell, this interference effect actually confirms that the stylet chemistry is characterized by its
calcite content.
And do not forget that those minute calcite tools with a thickness of a few microns
are actually working tools for everyday feeding which is a kind of miracle, of course.
Moreover due to the fact that, even in this tiny dimension they are said to be hollow
for an optimum weight/durability ratio!
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