Author: 
Ekaterina Сhornaya 

Title:
The 10-µm silicate feature in compact olivine particles

Abstract.
We experimentally measure the mid-IR spectra of half-millimeter-sized 
olivine particles with very compact morphology and smooth surfaces. 
We find that the 10-micron silicate feature is present in these large, 
irregularly shaped samples having surface roughness that is much smaller 
than optical wavelengths. Based on Mie theory, which assumes the particles 
are spherical, this feature should not exist for such large particles. 
As a consequence, its presence has been taken as an indicator that the particles 
or grains composing such particles were micron-sized or smaller.
The measurement of this feature in real particles that radically violate this 
constraint suggests that the constraint is imaginary and likely the result 
of the assumption that the particles are spherical.