Crystal form determines flat-surface shape {fracture plane} that appears after breaking rock.
Rocks, such as diamond, can be shiny and lustrous {luster}|. Metals, such as silver, can be lustrous, because dielectric constant is negative.
Some rocks split light into two colors {pleochroism}.
Rocks have relative strength {hardness}|, depending on chemical-bonding patterns.
Hardness scale {Moh's scale} {Moh scale} goes from 1 to 10. Diamond is 10. Cubic boron nitride is 9.5. Corundum is 9. Quartz is 7. Glass is 6. Steel is 5. Fluorite is 4. Calcite is 3. Salt is 2. Talc is 1.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225