Mohs scale of mineral hardness integrity, they are not considered "scratches" for the determination of a Mohs scale number. The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (10) is four times as hard as corundum. The table below shows the comparison with the absolute hardness measured by a sclerometer, with pictorial examples. On the Mohs scale, a streak plate (unglazed porcelain) has a hardness of approximately 7.0. Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale. The table below
Worshipful Company of Scientific Instrument Makers or using scientific instruments. This could be any kind of scientific instrument: a measuring instrument, like a feeler gauge or an atomic clock, or an imaging instrument like a PET scanner. It might even be a piece of control engineering incorporating many instruments. What makes the Company a community is partly a shared interest in scientific instruments and, more generally, in science and engineering. It is also partly a shared love of good company, of meeting for discussion over food and wine, and of bringing partners or guests to a grand banquet in distinguished surroundings. But what makes the Company