Pumice is a volcanic rock, created when super-heated, highly pressurized rock is violently ejected from a volcano. It can be formed when lava and water are mixed. This unusual formation is due to the simultaneous actions of rapid cooling and rapid depressurization. The depressurization creates bubbles of gases and water dissolved in the lava, which rapidly separate from one another at a critical point of temperature, much like the bubbles of CO2 that appear when a carbonated drink is opened. The simultaneous cooling then freezes the bubbles in the matrix. It is commonly pale in color, ranging from white, cream, blue or grey, to green-brown or black as in the photo. Pumice used to make lightweight concrete, This form of concrete was used as far back in times. Roman engineers used it to build the huge dome of the Pantheon and many aqueducts. It is used today as an abrasive, especially in polishes, pencil erasers, cosmetics and to produce stone-washed-jeans. We also use "Pumice stones" as remover for dry skin as well as calluses. Ground pumice is added to some toothpastes and heavy-duty hand cleaners such as Lava soap as a mild abrasive. In ancient Greek and Roman times it was also used to remove excess hair.
Camera Sony DSC-H9
Focal length 5mm
F# f/5.6
Exposure 1/640
ISO 100