几种矿物晶形图的改正

CORRECTION FOR CRYS TAL DRAWINGS OF SOME MINERALS

正确的晶体定向，其晶体几何常数应与内部结构的晶胞参数一致。在“砂矿物图册”中，锐钛矿、锆石、钛石、磷钇矿、符山石、白钨矿、钼铅矿，其晶形的（１００）与单位晶胞的（１１０）相同，乃采用错误的旧定向所致。笔者对此作了改正：１．利用上述矿物的晶胞棱长，按新旧两种定向，计算出各矿物的晶面指数及其角度值，列表对照。２．通过作极射赤平投影或立体图的方法，对图形容量大而采用旧定向的“砂矿物图册”和目前国内唯一采用新定向的图形容量小的“矿物学导论”中的上述矿物的晶形图进行分析，并纠正其中错误部分。３．按新定向用极射赤平投影绘制晶体立体图的方法，绘出上述矿物的精确图形，并作简要的文字描述。

The geometric constants of a ctystal should be in accord with the cell parameters of thecrystal. In the book “Atlas of Placer Minerals”,however,the drawings of crystal form(100) ofanatase,zircon,thorite,xenotime,vesuvianite, scheelite and wulfenite are identical to those oftheir unit cell(110)due to the old,but wrong crystal orientation.Acorrection for these errors has been made by the author.First,the crystal plane indices andrelevent angles of these minerals are calculated according to both the old and new orientations;and the results are tabled and compared.second the crystal drawings of the above-mentionedminerals occurred in the Atlas of Placer Minerals in which the old orientation is used and also in the book In troduction to Mineral ogy in which the new or ientation usedare anlysed by means ofstereographic projection and errors thus found are corrected.Finally,precise crystal drawings ofthe above-mentioned minerals are plotted,each with a brief description,by means ofsteorographic projection according to the new orientation