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  Formula: KTiO(AsO4) 
  
  Arsenate, titanium-bearing mineral
  
  Crystal System: Orthorhombic
  
  Specific gravity: 3.49 calculated
  
  Colour: Colourless
  
  Common impurities: Fe(III)
  
  Environments
  
  Katiarsite is a relatively new mineral, approved in 2014 and to date (January 2025) reported only from the 
  type locality.
  
  Localities
  
  At the type locality, the Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure eruption, 
  Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia, katiarsite occurs in sublimates 
  encrusting basaltic scoria 
  around a volcanic fumarole. Associated minerals include hatertite, 
  bradaczekite, johillerite, 
  yurmarinite, tilasite, 
  arsmirandite, hematite, 
  tenorite, arsenic-bearing 
  orthoclase, 
  fluorophlogopite and 
  aphthitalite. Katiarsite occurs as long prismatic to acicular, 
  typically sword-like, crystals up to 3 μm × 10 μm × 50 μm in size 
  (MM 80.4.639-646, HOM). 
  
  Katiarsite from the Arsenatnaya fumarole - 
  Image
  
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