  Alunite. 
Description from the source: 
Alunite (KAl3(SO4)2(OH)6 trig.), La Tolfa, Civitavecchia, Lazio, Italy. Small crystal clusters on the same massive material from a classic italian locale. 3,8x2,2x1,5; 22 g. 
Source: Simone Citon 
Contributor: John Gray 
Acquired: 26 September, 2008 
Text Updated: 28 September, 2008 
Price: Trade 
Size: 1.5" 
Composition: KAl3(SO4)2(OH)6
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