I found a mineral near the hexagonal rock formations in High Island, Hong Kong that I'd like to get ID'd. It has a greasy and subadamantine lustre. It can scratch a U.S. Quarter Dollar and some types of glass. Some types of glass are able to scratch the mineral. It is translucent but with a yellow tint, with a tetragonal form. The front is flat, with some cleavages. Its streak is a white-yellow. The back is smooth and bumpy. The sides have a mark with an earthy red colour that may be an impurity.
Here is the front side:
Here is the back side:
Here is the side:
The distance between the 2 little marks is 1mm.