1.1. the quality or condition of being hard. E.g. people complained about the hardness of the chairs
2. brittle
2.1. hard but liable to break easily. E.g. her bones became fragile and brittle
3. rigid
3.1. unable to bend or be forced out of shape; not flexible. E.g. a seat of rigid orange plastic
4. malleability
4.1. (of a metal or other material) able to be hammered or pressed into shape without breaking or cracking. E.g. "a malleable metal can be beaten into a sheet"
5. thermal conductivity
5.1. the rate at which heat passes through a specified material, expressed as the amount of heat that flows per unit time through a unit area with a temperature gradient of one degree per unit distance.
6. density
6.1. the degree of compactness of a substance. E.g. "a reduction in bone density
7. waterproof
7.1. impervious to water. E.g. a waterproof hat
8. sonorous
8.1. capable of producing a deep or ringing sound E.g. the alloy is sonorous and useful in making bells
9. strength
9.1. the capacity of an object or substance to withstand great force or pressure. E.g. they were taking no chances with the strength of the retaining wall
10. flexibility
10.1. the quality of bending easily without breaking. E.g. players gained improved flexibility in their ankles
11. ductile
11.1. (of a metal) able to be drawn out into a thin wire. E.g. able to be deformed without losing toughness; pliable, not brittle.
12. electrical conductivity
12.1. the degree to which a specified material conducts electricity, calculated as the ratio of the current density in the material to the electric field which causes the flow of current.
13. absorbent
13.1. (of a material) able to soak up liquid easily. E.g. absorbent kitchen paper
14. transparency
14.1. the condition of being transparent. E.g. the transparency of ice