What Mineral is My Birthstone and what are its Properties?

What's My Birthstone?Crystals and gemstones have been associated with months of the year for almost 2,000 years. Today, we call them birthstones. Each birthstone is a unique mineral or mineraloid that has distinct characteristics.  What is your birthstone?

Garnet – January’s Birthstone

January’s birthstone is Garnet. Garnets are often found in metamorphic rocks such as schist. Garnets are actually a family of minerals which are all similar. The garnets which are often used as gemstones are typically a dark red color; however, the brilliant green of variety of uvarovite is rare and very prized.

Amethyst – February’s Birthstone

Amethyst is a common, purple form of the mineral quartz.  Fairly hard, amethyst is a 7 on the Mohs hardness scale which has a range from 1 (softest) to 10 (hardest).  Crystals of the mineral often form in clusters, which are also called druze, and also commonly form in geodes.  The purple color of amethyst is due to the presence of ferric iron (Fe3+) in the quartz crystal and can range from light to dark.  When heated, amethyst will turn brown, into citrine.

Amethyst is considered a semi-precious gemstone that is most commonly used in jewelry and for collecting.  Beautiful samples of amethyst can be found in Brazil, Mexico, Uruguay, Russia, India, Sri Lanka, and the United States.

Aquamarine – March’s Birthstone

Aquamarine is a pale blue form of the mineral beryl.  Aquamarine crystals can occur in such rocks as granite and pegmatite.

These beautiful gemstones have a glassy luster (shine) and are either translucent or transparent.  These properties make aquamarine a prized stone for all types of jewelry.

Diamond – April’s Birthstone

Did you know that pencil lead and diamonds are made of the same thing?  It is hard to believe but they are both made of carbon!  The carbon forms in different crystal types or shapes, which is why they are different.  Diamond is the hardest mineral, being a 10 on the Mohs hardness scale.

Diamonds form in igneous rocks called Kimberlites and Lamproites. These igneous rocks are typically rich in the mineral olivine and derive from mantle rocks known as peridotites. The peridotite rocks melt deep below the surface (between 90 and 280 miles) of the Earth then rise through cracks in the surrounding rock forming pipe-shaped intrusions. As the magma pushes its way through the cracks, some of the surrounding rocks break off and mix into the liquid magma. Over time, (millions of years) the magma slowly cools into rock with large crystals. Sometimes these crystals include those wonderful gemstones we know as diamonds.  This photo shows cores of kimberlite rock from a drilling and exploration project. The rocks cores are stored these long, then boxes for examination. Geologists store the cores in order as they pull them from the ground so that they can view the rocks in one long string and see exactly what is present below the land surface.

The largest diamond ever found is over 7,000 carats which is about the size of your two fists put together.  Because of their beauty and strength, diamonds are used for a wide variety of products from jewelry to industrial cutting blades. The photo at the top left shows a group of different sized diamonds which have been cut and faceted.

Emerald – May’s Birthstone