Opacity : the quality of lacking transparency or translucence.
Transparence : the quality of being clear and transparent
Firmness : not soft or yielding when pressed, not shaking or trembling
Iridescence : the visual property of something having a milky brightness and a play of colors from the surface
Slum : a squalid and overcrowded urban street or district inhabited by very poor people
Poverty : the state of being extremely poor