Langite
Cu₄(SO₄)(OH)₆ · 2H₂O

     Langite is another rare species at MSH.

PHYSICAL CHARACTERISTICS:

Color is usually greenish-blue.
Luster is vitreous to silky.
Diaphaneity is transparent to translucent.
Crystal System is monoclinic; Pc.
Crystal Habits include efflorescences.
Cleavage {001} and {010}.
Fracture is uneven.
Hardness is 2.5 - 3.
Specific Gravity is approximately 3.25 g/cm³.
Streak is white.
Associated Minerals include UK #55.
Distinguishing Features: Crystal habit.
Origin: Named in 1864 after Victor van Lang (1838-1921),
   Austrian professor of physics.

CLASSIFICATION:

REFERENCES:
Dana 8:644 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE: