THE NATURE OF WATER IN CHALCEDONY AND OPAL-C FROM BRAZILIAN AGATE GEODES
THE NATURE OF WATER IN CHALCEDONY AND OPAL-C FROM BRAZILIAN AGATE GEODES
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DOI：
10.1007/bf00310343
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发表时间：
1985-01-01
影响因子：
1.4
通讯作者：
MIEHE, G
中科院分区：
文献类型：
--
作者：
GRAETSCH, H;FLORKE, OW;MIEHE, G
采用热分析、化学分析和红外吸收等方法研究了巴西玛瑙中不拉长玉髓和蛋白石C的水形态（H2O（SiOH）和H2O（mol））。用BET氮吸附法测定了玉髓和蛋白石C的比表面积和比密度，发现玉髓和蛋白石C在开孔处具有完全水化的晶体表面。它们在内表面含有额外的水，在蛋白石-C的情况下是封闭的微孔，在玉髓中是累积缺陷的区域（例如双晶层边界）。所有表面都覆盖着硅醇基团，与分子水形成氢键。另外的羟基，弱氢键的微晶内的结构框架，位于结构点缺陷。壁衬玉髓的范围从半透明的灰色到乳白色白色带，对应于总水含量、H2O（SiOH）/H2O（摩尔）比、BET表面和密度的增加。H2O（SiOH）/H2O（摩尔）比是敏感的后续水热处理，并表明低温形成的玉髓。
The water species (H2O(SiOH)and H2O(mol)) of length-fast chalcedony and opal-C in Brazilian agates were studied with thermoanalytical, chemical and infrared absorption methods. Specific surfaces were measured with the BET nitrogen adsorption method and the specific densities were determined.Chalcedony and opal-C have fully hydrated crystal surfaces at the open porosity. They contain additional water at inner surfaces, which are closed micropores in the case of opal-C and regions of accumulated defects (e.g. twinlamellae boundaries) in chalcedony. All surfaces are covered with silanole groups, hydrogen-bonded to molecular water. Additional hydroxyl groups, weakly hydrogen bonded to the structural framework within the crystallites, are located at structural point defects. Wall-lining chalcedony ranges from translucent gray to milky white bands corresponding with decreasing total water content, the H2O(SiOH)/H2O(mol)-ratio, BET-surfaces and increasing density. The H2O(SiOH)/H2O(mol)-ratio is sensitive to subsequent hydrothermal treatment and indicates a low temperature formation of chalcedony.