Annite
KFe₃²⁺(AlSi₃O₁₀)(OH,F)₂

     A member of the mica group, annite is indistinguishable from biotite and is uncommon at MSH.

PHYSICAL CHARACTERISTICS:

Color is usually black or dark green.
Luster is vitreous to submetallic.
Diaphaneity is transparent to opaque.
Crystal System is monoclinic; C2/m.
Crystal Habits include large well-formed pseudohexagonal prisms
    to 12cm across and 15cm long.
Cleavage: {001} is perfect.
Fracture is uneven.
Hardness is 2 - 3.
Specific Gravity is approximately 3.3 g/cm³.
Streak is white.
Associated Minerals include microcline.
Distinguishing Features: Crystal habit and color.
Origin: Named in 1868 after its discovery locality at Cape Ann,
    Essex county, Massachusetts, U.S.A..

CLASSIFICATION:

REFERENCES:
MinRec 21:296 (1990), Dana 8:1461 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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