Mineral Information and Data:

Alum-(Na)
NaAl(SO4)2 • 12H2O [CNMNC approved formula]

Named in 1875 ; renamed in 2008 for the dominant element Na and the Latin, alumen.

IMA status : Renamed IMA Approved; 2008 ()
CLASSIFICATION 
Dana
(8th edition) :
29.05.05.02  
  (29) Hydrated Acid and Sulfates
  (29.05) where A B (XO4)2 · x(H2O)
  (29.05.05) Alum Group
  
Nickel-Strunz
(10th edition) :
07.CC.20
  (07) Sulfates (selenates, tellurates, chromates, molybdates, wolframates)
  (07.C) Sulfates (selenates, etc.) without Additional Anions, with H2O
  (07.CC) With medium-sized and large cations
  
Crystal system: Cubic System
Point group (H-M): m3 (or 2/m 3) — diploidal
Unit cell: a = 12.133 Å
Crystal Habit: Crystals fibrous
  
Color: Colorless
Diaphaneity: Transparent
Luster: Vitreous
Hardness (Mohs): 3
Measured Density: 1.67 g/cm3
  
  
Synonyms/varieties: Sodium-alum
Other Properties: H2O Soluble.
Comments: Soda - Renamed to Alum-(Na) : Mineralogical Record, v39 (2008), p131

 

Alum-(Na)
A massive chunk of alum-(Na)
Origin: Wayne Co., Utah, USA
Sample size: big and massive
Photo Copyright © Rockpick Legend Co. & Rick Dalrymple

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