Geomview itself does not fully support transparency yet and on some machines it does not work at all. This slider controls the diffuse reflectance of a surface. This has to do with how much the surface scatters light that it reflects. This slider controls how shiny a surface is. This determines the size of specular highlights on the surface.
Lower values give the surface a duller appearance.
This slider controls how much of the ambient light a surface reflects. This slider controls the specular reflectance of a surface. This has to do with how directly the surface reflects light rays. Higher values give brighter specular highlights. Done This button dismisses the Materials panel.