Mineral Information and Data:

Akatoreite
Mn2+9Al2Si8O24(OH)8 [CNMNC approved formula]

Named for the locality: three km south of Akatore Creek, east Otago, South Island, New Zealand.

IMA status : Approved Species 1969 (IMA1969-015)
CLASSIFICATION 
Dana
(8th edition) :
57.02.03.01  
  (57) Sorosilicate Insular Si3O10 and Larger Noncyclic Groups
  (57.02) with [Si4O13] groups
  (57.02.03) Akatoreite Group
  
Nickel-Strunz
(10th edition) :
09.BH.15
  (09) Silicates
  (09.B) Sorosilicates (dimer) structures
  (09.BH) Sorosilicates with Si3O10, Si4O11, etc. anions; cations in tetrahedral [4] and greater coordination
  
Crystal system: Triclinic System
Point group (H-M): 1 — pinacoidal
Unit cell: a = 8.337 Å, b = 10.367 Å, c = 7.629 Å, a = 104.46°, b = 93.81°, g = 104.18°
Crystal Habit: Crystals prismatic, elongated and striated parallel to a-axis; massive to radiating
Twinning: on {021}; twin axis perpendicular {021}, lamellar in thin section
  
Color: Yellow-orange to orange-brown
Diaphaneity: Transparent
Luster: Vitreous
Hardness (Mohs): 6
Measured Density: 3.8 g/cm3
Cleavage: 2; {010} excellent; {012} imperfect
Streak: Yellow white
  
Geologic Setting: In a manganiferous metachert and carbonate lens in schists (Akatore Creek, New Zealand); in manganiferous potassium-rich felsic metavolcanics (Norberg, Sweden).
Mineral Association: Rhodochrosite, pyroxmangite, rhodonite, spessartine, quartz, tinzenite, apatite, todorokite, alabandite, hÄubnerite (Akatore Creek, New Zealand); ganophyllite, rhodochrosite, pyrolusite (Norberg, Sweden)
  

 

Akatoreite
Brown akatoreite in pink rhodonite.
Origin: Akatore Creek, Eastern Otago Peninsula, South Island, New Zealand.
Photo: Jeff Weissman

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