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
95-99 George Street, The Rocks buildings form an integral part of what was the major commercial centre of the colony, which has continued in the same use to the present day. As a group, the shops along the western side of George street have a landmark streetscape value, providing a strong architectural statement on the major entry into The Rocks. While differing in style, the buildings are sympathetic in materials and scale and form a unified visual precinct, and make a major contribution to the significance of The Rocks Conservation Area. The sites have strong associations with former uses and owners including the early penal