Galery 1, ammonium cobalt sulfate

Lab Grown Crystals Picture Galery

 

 


© 1998 by Udo J.A. Behner

"Ammonium Cobalt Sulfate"

e.g. ammonium magnesium sulfate doped with cobalt

chemical formula : (NH4)2(Mg, Co)(SO4)2 · 6 H2O
crystal class : monoclinic prismatic
growing method : slowly cooling of the aquaous solution
growing time : app. 7 days
crystal size : up to 5 centimeters

This is a huge specimen of so called ammonium cobalt sulfate but however this is only cobalt doped ammonium magnesium sulfate.
Its an example of the Tuttons Salts which have the general formula X2Y(ZO4)2 · 6 H2O where X represents either K(Potassium), Rb(Rubidium), Cs(Caesium), Tl(Thallium(I)) or NH4(Ammonium) and
Y can be Mg(Magnesium), Zn(Zink), Mn(Manganese(II)), Cu(Copper(II)), Ni(Nickel(II)), Co(Cobalt(I)), Fe(Iron(II)), Cd(Cadmium), Cr(Chromium(II)!) and V(Vanadium(II)!).
The anion ZO4 may be represented by SO4(Sulfate), SeO4(Selenate) or CrO4(Chromate).
Its supposed that they can form mixed crystals all together so far as they are chemical compatible.
I have also been growing pure ammonium cobalt sulfate which is dark red in color with a little brownish to purple hue, but due to the high price of cobalt I use this expensive ingridient only as a "dye" to get various color shades of pink and red in ammonium magnesium sulfate.
This specimen is currently exhibited at the mineral museum in Pforzheim.

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