今天很少有动物去吃这种植物，因为这种植物含有很多硬硅酸盐类物质，这种物质对牙齿很不好。

Few animals feed on them today because they contain a lot of hard silicate which is bad for teeth.

youdao

这种物质硬如磐石（石灰石主要就是由碳酸钙构成的），但易溶于酸。

The stuff is tough as a rock (limestone is made primarily of calcium carbonate), but it dissolves instantly in acid.

youdao

如果要检测硬度，陨石的标本就太小，它只能显示出这种物质无疑比一般钻石硬。

The sample from the meteorite was far too small to test for hardness, except to show that it is certainly harder than regular diamonds.

youdao

I'm the heterogeneous system, soft stuff, hard stuff, liquid stuff.

我是非均匀系统，有软的物质，硬的物质，液体物质等。

麻省理工公开课 - 热力学与动力学课程节选