Crystal Lovers, have we got a treat for you! In this blog post we’re going to briefly talk about the Geology of Garnet.
When most folks hear the term garnet they are thinking of the classic deep red gemstone. Turns out, Garnet is an entire group of minerals that share the same growth pattern; a cubic crystal system that forms a dodecahedron and mineral composition consisting of Magnesium Silicate, Iron, Calcium, and Aluminum.
Mixtures that have larger amounts of Magnesium are called Pyrope Garnet and those that have larger amounts of Iron are called Almandine Garnet. There are more types, but these are the most common. As it turns out, the green variety of Garnet is a whole other amazing ballgame. We’ll get to those a little later in this post.
The Garnet family hardness typically runs between a 6.5 – 7.5 depending on the composition and is of pretty “low value” because of the abundance of this crystal around the globe. The plus in this is that when you find it on the market it’s the real thing; garnet is not usually produced synthetically for the commercial market and is often sold without any additional treatment. If imitations are found on the market, they are usually glass.
Garnet has a long history of use among humans going back at least 5,000 thousand years. It has even been found in Egyptian burials and was perhaps, the most popular gemstone in the ancient Roman Empire. Even Aristotle spoke of the beauty of this stone. This long history speaks to its hardiness.
Speaking of ancient Greece; many of the names we know today to describe the Garnet family come from this culture. “Pyrope” for example is the term that is used for fire. The name we know today, Garnet, was introduced by the philosopher Albertus Magnus and is Latin for ‘seed like’ as garnet in its matrix can look a lot like the seeds of red pomegranate.
Magnus wrote about his observation of Garnet as grains in other rocks and loose in the soil. Garnet can be found in all 3 classes of rocks and fun fact; most garnets found close to the earth’s surface typically contain higher amounts of aluminum.
Most Garnet forms at convergent plate boundaries like we have here in Washington state. They start off as tiny grains and get bigger over time. This said, you can absolutely find garnets in Washington state casually walking around in the right spot!! According to Gem Trails of Washington by Garret Romaine; Garnet can be found in Darrington, Heather Lake, Money Creek, and on Ruby Beach.
In areas that produce Diamonds, Garnet is also used as an indicator mineral for kimberlite, peridotite, and eclogitic rocks. Kimberlite is a matrix that diamonds can be found in, especially in the Kimberly district of South Africa and sometimes Siberia.
The Garnet can be found on nearly every continent in the world and it is only in the last 150 years that humans have found uses for Garnet in the industrial sector for water-jet cutting, abrasive blasting, water filtration, and abrasive powders.
The calcium-based garnets, typically green in color, are lower in specific gravity and as such tend to have a lower hardness on the MOHS Scale. This makes sense when we look at the periodic table of elements. Iron (Fe #26)) is a much stronger substance than Calcium (Ca #20) and even when exposed to the elements; Iron will weather and erode a lot slower than calcium will.
Calcium based Garnets, like tsavorite, often from when limestone is chemically altered into marble via contact metamorphism.
From black, red, blue, violet, to green and even some shades of orange and yellow; the garnet family is just as vast as it is beautiful! We’ve got great specimens of raw Garnet and Garnet in matrix in the store that pictures will never quite do the proper justice.
Stop by Crystal spirit Spiritual Center this week to check them out for yourself.
Check back next week as we talk about the metaphysical properties of Garnet and how it can be used during February; the month of love.
Also, don’t forget to subscribe to our YouTube! Every blog post about a stone has a short video that goes with it 😊, Garnet will be up next week!