"A pair of scissors consists of two pivoted blades. In lower-quality scissors, the cutting edges are not particularly sharp; it is primarily the shearing<span> action between the two blades that cuts the material. In high-quality scissors, the blades can be both extremely sharp, and tension sprung - to increase the cutting and shearing tension only at the exact point where the blades meet. The hand movement (pushing with the thumb, pulling with the fingers) can add to this tension. An ideal example is in high-quality tailor's scissors or shears, which need to be able to perfectly cut (and not simply tear apart) delicate clothes such as chiffon and silk."</span>
The difference between a mineral and a rock is (C) A rock is generally made up of an aggregate of minerals, but this is not a requirement. Rocks can also be made up of non-mineral matter.
