General:
     The studied area in this research is located in sw Birjand (S Khorasan). The vast outcrop of listventites is the most interesting geological phenomena in this area . Ingeneral, listvenites has formed in alcali condition by co2 enrichment hydrothermal
solutions. During this reactions,primary paragenesis of minerals is changed to silisic-carbonate assemblages. This process generally occurred at locality in which there is chanals for transport of hudrothermal solution. Fault zone, bedding surfaces, rock unit bounddary are the most important locality that linear trend of
Iistvenite shows it. From physicochemical aspect, this
reactionhappened in conditions with PH about 10-12 by co2
enrichment solution (winkler). Form thermodynamic aspect. based on changes of T versus xco2 (in P constant), reactions containing
CO2 and HO2 divided in five groups in which listvenitation reacation is situated in carbonation- dedydration group and its carve have a negative slope meaning that with increasing of XCO2,
the low temperature is required for reaction (greenwood 1976).