Peridot Properties Facts and Photos

What is Peridot?

Peridot is the gemstone variety of the mineral olivine, one of Earth's most common minerals.

It's one of only a few gemstones that occur in just one colour. Depending on the amount of iron present, the shade can vary from deep green to yellowish-green to brownish-green.

Peridot with more iron tends to be a deeper shade of green or brownish-green.

Peridot is idiochromatic, meaning its colour comes from the mineral's chemical composition, not impurities. 

Although most gemstones form in Earth's crust, peridot and diamond originate much deeper, in the layer known as the upper mantle.

Peridot, which forms in peridotite rock, reaches the surface through volcanic eruptions or tectonic activity.

Some peridot is estimated to be around 4.5 billion years old.

Flaws in peridot are common because of the intense forces that bring it to the surface. This is also why large stones are rare.

Olivine, a magnesium iron silicate, is believed to make up as much as 50% of the upper mantle. It has been found in meteorites, on the moon and Mars.

According to the Modern Birthstone Chart, peridot is the birthstone for August. On the Traditional Birthstone Chart, it's an alternative to sapphire. Peridot is also associated with the zodiac sign of Libra.  

Although often pronounced per-i-dot, the correct pronunciation is per-i-dough.

Despite the abundance of olivine, gem-grade peridot is quite rare.

The History of Peridot

One of the earliest references to peridot was by the ancient Roman author and philosopher Pliny the Elder. In his encyclopaedia Naturalis Historia, he talks of a stone presented to Berenice, Theban queen of Lower Egypt, around 300 B.C.

In the Bible's Book of Exodus, it's written that peridot was the second stone in the first row of the high priest's breastplate. This religious garment was worn by Aaron, the first Jewish high priest.

In ancient texts, peridot is believed to have been known as topazos. Historically, this has caused no end of confusion with the mineral topaz.

Most of the early peridot was mined on the island of Topazos. Today, this island in the Red Sea is known as St John's Island or Zabargad in Arabic. Small amounts of peridot can still be found there.

Stones from this location have excellent colour and sharp, lustrous and well-defined crystal faces.

In later years, large gem-grade peridot was found in Myanmar, formerly Burma. These mines became well known for their twenty and forty carat stones which exhibited exceptional colour and clarity.  

Ancient Egyptian rulers called peridot 'the gem of the sun' because of its intense brightness. They believed it could not be mined during daylight because the brightness rendered it invisible.

In the dark, peridot was believed to give off its own light. The location could then be marked so miners could return by day to collect stones.

More About Peridot

A particularly unusual characteristic of the mineral olivine is it's highly susceptible to chemical weathering. For this reason, stones don't survive for long on the surface in wet climates.

This is why peridot can only be found in a few places. It tends to be restricted to areas with arid or semi-arid climates.

Inclusions in peridot are common and, when present in abundance, can cause the stone to become opaque. The most notable inclusions, known as lily-pad inclusions, are disc-shaped fractures that resemble lily pads.

Another common inclusion in peridot is small black or dark brown chromite crystals, which appear as tiny black spots visible under magnification.

A significant quantity of fine-grade peridot from the Suppatt region of Pakistan appeared on the market in 1992. The deposit is 15,000 feet up in the Kashmir region of the Himalayan Mountains. This inhospitable and rugged terrain is prone to landslides and heavy winter snow.

Peridot from this area can only be mined from late June to early September.

Some of the finest-grade peridot from Pakistan ever discovered was mined around the year 2000. The size of these stones was described as "quite magnificent". Once cut, some weighed over 2000 carats.

Peridot Mesa on the San Carlos Apache Indian reservation in the United States is currently the most productive peridot mining area in the world. It's estimated eighty to ninety five per cent of the world's peridot comes from here.

Peridot can also be found in Australia, Brazil, China, Egypt, Norway and other parts of the USA.

Peridot grades 6.5 to 7 on the Mohs scale of mineral hardness. Although quite hard, it's also brittle.

Article Pictures

The mineral olivine in the picture at the top of our article is courtesy of Stan Celestian. 

The raw peridot in the second photo is from our collection.

The peridot in the next photo is in the Smithsonian Museum of Natural History, Washington D.C. Photo by Stone Mania.

Photos 1 and 3 are clickable and redirect to the original image.

Pop-up photos: Pallasite meteorite (with olivine crystals) - Courtesy of Ron Wolf.