Dull Lustre
Dull (or earthy) minerals exhibit little to no lustre, due to coarse granulations which scatter light in all directions, approximating a Lambertian reflector. An example is kaolinite. A distinction is sometimes drawn between dull minerals and earthy minerals, with the latter being coarser, and having even less lustre.
Read more about this topic: Lusters, Common Terms
Famous quotes containing the words dull and/or lustre:
“Our live experiences, fixed in aphorisms, stiffen into cold epigrams. Our heart’s blood, as we write it, turns to mere dull ink.”
—F.H. (Francis Herbert)
“How much on outward show does all depend,
If virtues from within no lustre lend!
Strip off th’externals M and Y, the rest
Proves Majesty itself is but a Jest.”
—Horace Walpole (1717–1797)