Lapis Lazuli, Rock On!

  
      It’s finally time for my first blog about a rock and not a mineral. Lapis lazuli is a blue rock that has been prized since ancient times. What makes a rock differ from a mineral? you may ask. A mineral is an inorganic substance with a definite chemical formula. A rock is simply a mixture of minerals. You can think of a mineral as a simple substance such as sugar or salt and a rock would be a mixture of other substances like a cake or salad dressing. Lapis lazuli is a rock that is composed of the minerals lazurite, sodalite, hauyne, calcite, and pyrite. Lapis lazuli receives its blue color from the mineral lazurite and the pyrite present within the rock will sometimes dot the stone with brassy flecks. The mineral calcite is sometimes visible as streaks of white material throughout the rock. Being a rock lapis lazuli has no crystal structure, but is instead found in giant amorphous lumps. The word amorphous means ‘without shape’ or ‘no shape’ and means that the thing in question has no definite shape and is found in random chunks. A few minerals have been known to form amorphous specimens, but these huge lumps are composed of a great deal of tiny crystals that all have definite shapes. Lapis lazuli has no definite shape because it is a mixture of minerals.
     I only know of a few uses for lapis lazuli. The first is as a decorative stone. Lapis lazuli has what I would call a medium hardness (it measures about 5 ½ on the Mohs’ Scale) so it can be carved and polished fairly easily. Both the ancient Egyptians and the Babylonians used lapis lazuli to make carvings. I have personally seen photographs of mosaics, scarabs, and figurines that were made from lapis lazuli in ancient Egypt. Tutankhamen’s mask was inlaid with the stone as well. Lapis lazuli was also ground to make a blue-colored paint in ancient Persia, though this was a very rare use of the rock because the mineral azurite was softer and a lot less expensive than lapis lazuli. Today Lapis lazuli is still used to make carvings and rock and mineral collectors also love to have natural, un-carved, pieces in their collections.
Lapis lazuli is found in Argentina, Chile, the former USSR, and the United States. The most famous source of the blue rock is Afghanistan where it has been mined for thousands of years. Most of the lapis lazuli that was used by ancient peoples probably came from Afghanistan. In fact, the lapis lazuli that is found upon King Tutankhamen’s mask came from that country.
     Lapis lazuli is beautiful when compared to most other rocks, and even when compared to some minerals. It is certainly the only blue rock that I know of!