Rapid dissolution of minerals at microasperities in super-critical and sub-critical H2O

利用纳米压痕试验机，在300 mN载荷下对石英单晶样品进行压痕试验(点接触变形)，然后将样品浸泡在高温高压(350℃，20 Mpa)压力容器中产生的亚临界H2O中2小时。我们用激光显微镜观察了样品从亚临界H2O中去除后的压痕区域，发现压痕中的石英迅速溶解，而远离压痕的完整石英没有明显溶解。我们测量了石英的溶解体积，发现LOG(压痕深度)与LOG(溶解石英体积)之间存在线性关系。我们还考察了石英晶体取向对压痕深度与产生压痕所需能量之间关系的影响，并得出结论：晶体取向对这种关系没有影响。

Indentation tests (point-contact deformation) were performed using a nano-indentation tester with a load of 300 mN on a specimen of single crystal of quartz, and then the specimen was immersed in the sub-critical H2O generated in a pressure vessel at high temperature and pressure (350 deg C, 20 MPa) for two hours. We observed the indentation area of the specimen after the removal from the sub-critical H2O with a Laser microscope, and noticed that quartz in the indentation rapidly dissolved whereas intact quartz far from the indentation did not appreciably dissolved. We measured the dissolved volume of quartz and revealed a linear relationship between log(depth of indentation) and log(volume of resolved quartz). We also examined the influence of crystallographic orientation of quartz on the relationship between the depth of indentation and the energy required to produce the indentation, and concluded that crystallographic orientation has no influence on the relationship.