Temperature regime and geochemical conditions of formation of danburite

Raman study of datolite CaBSiO4(OH) at simultaneously high pressure and high temperature

“…Therefore, datolite is not dehydrated at these P–T conditions, which correspond to the ‘cold’ zones of slab subduction. The question of whether datolite decomposes to provide water and boron at substantially higher temperatures T ~700–800 °С, which correspond to the ‘hot’ zones of slab subduction, requires further experiments.…”

“…Calcium borosilicates, datolite CaBSiO 4 (OH) and danburite CaB 2 Si 2 O 8 , occur in a wide range of conditions of geological environments . Datolite and danburite are stable with respect to other calcium borates in the system CaO–B 2 O 3 –SiO 2 –H 2 O at temperature 250 °C and pressure 0.1 GPa . Several dominating phases are crystallized in this system: datolite, danburite, wollastonite (CaSiO 3 ), and quartz.…”

“…Several dominating phases are crystallized in this system: datolite, danburite, wollastonite (CaSiO 3 ), and quartz. At low temperature (<200 °C) and high activity of acid H 3 BO 3 , datolite reacts to form the borate mineral CaB 6 O 9 (OH) 2 · H 2 O (nobleite type) and quartz: CaB 6 O 9 (OH) 2 .…”

Distinction of Natural and Synthetic Ametrine by Microscopic Examination—A Practical Approach

“…However, the minor changes recorded for this intensity ratio were not confirmed as being diagnostic for identifying heat treatment. (Kurshakova, 1982;Anovitz and Grew, 1996). Gem-quality yellow danburite is known mainly from Tanzania, Madagascar and Myanmar (Kiefert, 2007;Chadwick and Laurs, 2008;.…”

Danburite‐bearing calc‐silicate rocks from the Ascot Hills, Dookie, Victoria

“…These diverse environments indicate that danburite may crystallise over a considerable range in temperature and solution compositions (Kurshakova 1982). However, only recently have data become available on factors affecting its stability relations with other calcium borosilicates, in particular datolite (Semenov et al 1988;Yang & Rosenberg 1995).…”