Mineral powders are good crystalline, and they break along the cleavage plane when they are comminuted, which cause the mineral powders have flat surfaces and sharp edge angles.

但是由于矿物晶体粉碎过程中表现出沿解理面解理破裂的强烈倾向，使得矿物粉体表面具有平整的解理面及尖锐的棱角。

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He produced a sharp leg-break and Pietersen decided to attack it, his drive skewing off the edge waist high to a gratfeul Dravid.

BBC: England facing follow-on at Oval