© 1998 by Udo J.A. Behner
| chemical formula | : (NH4)2Fe(SO4)2 · 6 H2O |
| crystal class | : monoclinic prismatic |
| growing method | : slowly cooling of the aquaous solution |
| growing time | : about 5 days |
| crystal size | : up to 5 centimeters |
This is an odd example how slowly cooling a very hot solution produces big but not so well developed crystals.
The ammonium ferous sulfate is somewhat sensitive to heat, when you cook the solution it will turn opaque and
yellowish brown and the result are these crystals.
Moderate heating up to 50 or 60 °C produces the smaller but
better developed crystals in the picture before.
This specimen is currently exhibited at the mineral museum in Pforzheim.