Agardite-(Y)

Agardite is a mineral group consisting of agardite-(Ce), agardite-(Nd), agardite-(La), and agardite-(Y). They comprise a group of hydrous calcium, copper arsenate minerals which contain variable amounts of the rare elements cerium, neodymium, lanthanum and yttrium as well as trace to minor amounts of other rare earth elements. The general formula is (Ce,La,Nd,Y,Ca)Cu6(AsO4)3(OH)6·3(H2O). They form needle-like yellow green crystals in the hexagonal crystal system. The Mohs hardness is 3 to 4 and the specific gravity is 3.72.
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General Information:
 Chemical Formula:
(Y,Ca)Cu6(AsO4)3(OH)6·3(H2O)
 Composition:
(Molecular Weight = 1,030.82 gm)
Calcium 0.97 % Ca
Yttrium 6.47 % Y 
Copper 36.99 % Cu
Arsenic 21.80 % As
Hydrogen 1.17 % H 
Oxygen 32.59 % O 
 Empirical Formula:
Y0.75Ca0.25Cu6(AsO4)3(OH)6·3(H2O)
 IMA Status:
Approved IMA 1969
 Locality:
TL: Morocco, Bou Skour mine, Jebel Sarhro
 Name Origin:
Named for the composition and for Jules Agard, Geologist, Bureau de Recherches Geologiques et Minieres, Orleans, France.
Physical Properties:
 Color:
blue green or blue.
 Density:
3.66 - 3.72, Average = 3.69
 Diaphaniety:
Translucent
 Habits:
Acicular - Occurs as needle-like crystals., Rosette - Bundled tabular aggregates resembling rose flower petals., Spherical - Spherical, rounded aggregates.
 Hardness:
3-4 - Calcite-Fluorite
 Luster:
Vitreous (Glassy)
 Streak:
greenish white
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