THE POLISHABILITY OF SOME JORDANIAN LIMESTONES

Tests for acceptability of polish were carried out on six limestone types from Jordan using the average roughness, Ra and gloss meter values. These limestones are of different textures, strengths, and physical mechanical properties. The rocks were investigated in five consequent stages of polish: as sawn, diamond lap, SiC 600, SiC 1000, and diamond (1/4µm). The final stage of polish produced both the highest gloss and lowest roughness values. Crystalline limestone varieties produced the lowest roughness and highest gloss, while chalk produced the worst results in each case. Low porosity rocks gave the highest gloss and low roughness values. In high porosity stones, pores are exposed with continued polish resulting in little reduction of surface roughness. Roughness and gloss are both affected by the presence of impurities, which produced differential hardness and polishability within the rock.