Illite

Illite is a non-expanding, clay-sized, micaceous mineral. Illite is a phyllosilicate or layered silicate. Structurally illite is quite similar to muscovite or sericite with slightly more silicon, magnesium, iron, and water and slightly less tetrahedral aluminium and interlayer potassium. The chemical formula is given as (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)], but there is considerable ion substitution. It occurs as aggregates of small monoclinic grey to white crystals. Due to the small size, positive identification usually requires x-ray diffraction analysis. Illite occurs as an alteration product of muscovite and feldspar in weathering and hydrothermal environments. It is common is sediments, soils, and argillaceous sedimentary rocks as well as in some low grade metamorphic rocks. Glauconite in sediments can be differentiated by x-ray analysis.
See more at Wikipedia.org...

n. illite

General Information:
 Chemical Formula:
(K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]
 IMA Status:
Not IMA Approved
Physical Properties:
 Cleavage:
[???] Perfect
 Color:
white.
 Density:
2.6 - 2.9, Average = 2.75
 Diaphaniety:
Translucent
 Hardness:
1-2 - Between Talc and Gypsum
 Luster:
Earthy (Dull)
 Streak:
white
More details...

B: (Kimia) ilit
Built to Babylon by Hikmat Gumilar Visit my Website;