No, its not a portrait, but a pencil drawing of a beryl crystal. I did this sketch one evening when I was interstate for work, as well as a calcite sketch.
Beryl is better known as one of the gem forms. These include emerald (green), aquamarine (blue), morganite (pink) and heliodor (golden yellow). It is quite hard, which is why it is used for jewelry, and forms hexagonal prisms as can be seen in the drawing.
In Australia, one of the best known localities for beryl is the Triple Chance Mine, near Broken Hill, New South Wales. The metal beryllium was extracted from beryl from this location and used in the Apollo spacecrafts. Not gem-quality material though!