31. Beryl has a Mohs scale . so their toughness ( resistance to breakage ) is classified as generally poor. 32. On the Mohs scale , a streak plate ( unglazed porcelain ) has a hardness of 7.0. 33. The physical property of " hardness " is defined by the non-linear Mohs scale of mineral hardness. 34. It is soft ( not higher than 2.5 on the Mohs Scale ) and water-soluble. 35. An example of a well-established fact is that diamond scores 10 on the Mohs scale of hardness. 36. Published descriptions of these spheres being harder than steel are meaningless in terms of Mohs scale of mineral hardness. 37. An examination of several Klerksdorp spheres found none to be harder than 5.0 on the Mohs scale . 38. Greenish gray or bluish green in color, its Mohs scale and a density of approximately 6.44. 39. The crystals are brittle with a hardness of 5-6 on the Mohs scale and a white streak. 40. Diamonds are the hardest known naturally occurring substance and rate a 10 on the Mohs scale of mineral hardness.
