Mineralogical Properties of Traditional and Modern Birthstones
Birthstones are highly valued for their beauty and are often given as gifts to friends, family, and sweethearts.
Gemstones have been used for centuries to symbolize the month in which a person was born. These gems are naturally occurring minerals found in many types of rock. References of birthstones are found in the bible in the Book of Revelations, where they are listed as the twelve foundation stones of the New Jerusalem. The tradition of wearing birthstones was popularized in Poland in the fifteenth century. During this time, not only would people wear their own birthstone, but they would wear the stone of every month during that month, as it was considered good luck.
The Twelve Birthstones
There are both traditional and modern birthstones that symbolize the month of every year in the Gregorian calendar starting with January and ending with December. Some months have the same birthstone in both the traditional and modern lists, but others are different. Birthstones are usually referred to using their gemstone name, but in some cases, they have only one name which is their true mineral name.
The Mineral Families of Birthstones
The twelve birthstones and their corresponding mineral families are:
- January – Garnet (traditional and modern) which is also the mineral name for this gemstone.
- February – Amethyst (traditional and modern) is a form of the mineral quartz and is the most highly valued of the quartz group.
- March – Bloodstone or Jasper (traditional) are both forms of the mineral chalcedony, which is related to the quartz family, and Aquamarine (modern) is a form of the mineral beryl.
- April – Diamond (traditional and modern) or Sapphire (traditional). Diamond is a mineral, also the hardest substance on Earth, and sapphires are the gemstone form of the mineral corundum.
- May – Emerald (traditional and modern) or Agate (traditional). Emeralds are another variety of the mineral beryl and agates are another variety of the mineral chalcedony.
- June – Emerald, and Alexandrite (traditional) which is a form of the mineral chrysoberyl, or Moonstone and Pearl (modern). Moonstone is a feldspar mineral with a pearly and transparent luster. Pearls are organically made and lack a crystalline structure, so are not considered minerals. However, they do contain the mineral calcite.
- July – Ruby (traditional and modern), like the gemstone sapphire, is of the corundum mineral family. There is also Onyx (traditional) which is related to the quartz family.
- August – Sardonyx and Carnelian (traditional) which are both related to the quartz family, or Peridot (modern) which is the gemstone form of the mineral olivine.
- September – Sapphire (traditional and modern) or Peridot (traditional).
- October – Tourmaline (traditional and modern) which is a silicate mineral, Aquamarine (traditional), and Opal (modern), which is a mineraloid, meaning that it is not a true mineral due to its lack of a crystal structure.
- November – Citrine (traditional and modern), which is a variety of quartz, and Topaz (traditional and modern), which is a silicate mineral.
- December – Zircon, and Ruby (traditional) or Turquoise and Blue Topaz (modern). Zircon is a mineral and Turquoise is a mineral that is made up of the elements copper and aluminum.
Mineralogical Properties of Birthstones
The mineralogical properties of birthstones depend entirely on what type or variety of minerals they are. For example, anything in the quartz family, which includes the mineral chalcedony (amethyst, bloodstone, jasper, agate, onyx, sardonyx, carnelian, and citrine) are all going to generally have the same properties as quartz, except for some differences due to color, which are directly related to different elements making their way into the main silica bonds. However, since the main silica bonds are still intact, properties such as hardness and density remain the same. This is also true of the birthstones related to the beryl family (aquamarines and emeralds) and the corundum family (sapphires and rubies).