The terms epidote and zoisite are popular mineralogy terms that get thrown around.
However, not everyone is familiar with them or how they differ.
So if you’re new to the world of rocks and minerals or even if you have many years of experience identifying stones, perhaps this article about epidote and zoisite will help you out!
Epidote vs Zoisite (Explained)
What are Zoisite and Epidote?
Both epidote and zoisite are members of the same mineral family as epidote group minerals.
The epidote group includes several other minerals, such as allanite, piemontite, and clinozoisite.
Epidote is a green mineral that forms in many different colors, while zoisite is a brownish-green mineral that rarely forms in any other color.
Zoisite is a trichroic mineral which means that when light passes through it, you can see different colors in different directions.
When you look down at the stone, you can see its yellow-green color with reddish-brown streaks running through it.
When you look at the stone sideways, you can see its yellow-green color with black lines running through it.
Epidote is a minor ore of lead and zinc and forms in many rocks.
It is found in granite, basalt, gneiss, and schist. It also occurs in contact with metamorphic rocks and skarns.
Zoisite is a pink to green mineral containing calcium and aluminum silicate.
It makes up the bulk of the rock known as tanzanite, found only in Tanzania.
The two minerals are closely related because they share the same crystal structure.
This means that epidote may sometimes change into zoisite over time through metamorphism.
Epidote is a mineral whose name comes from the Greek word epidosis, which means “increase.”
How to Identify The Stones
Epidote and zoisite are very similar stones.
They are both a form of aluminum silicate, and they form in similar locations.
It can be challenging to tell them apart with the naked eye because they look almost identical.
Both epidote and zoisite come in a range of colors, including blue-green, brown, and even pink.
They can look very similar as these stones tend to be translucent glassy.
How can you tell them apart?
The best way is by testing their hardness on the Mohs scale.
Epidote comes in many forms, with varying hardness and luster.
The most common form of epidote is epidote in quartz, which has a vitreous luster and a hardness of six on the Mohs scale.
Zoisite is also a general name for a mineral group of silicate minerals.
Zoisite comes in many forms, with varying hardness and luster.
The most common form of zoisite is tanzanite, which has a vitreous luster and a hardness of six to seven on the Mohs scale.
If you try to scratch the stone with a knife blade or another hard object, and it doesn’t leave a mark, you have an epidote.
If it does leave a mark, it is a zoisite. However, note that some types of epidote are so soft they will mark easily as well.
The second difference between these two stones is that epidote is generally green.
In its pure form, epidote is colorless, but it can contain impurities that will give it a green color, whereas zoisite is usually pink.
This difference is due to the presence of iron in the epidote, which gives it its green tone.
While in the case of zoisite, the presence of manganese gives it its light pink coloration.
However, there are some varieties of each stone that don’t always follow this color scheme.
There are some varieties of epidote that can be brown or black due to manganese or iron oxides.
There are also varieties of zoisite that can be yellow due to calcium or green due to epidotization.
Zoisite is also said to be more expensive than epidote and is mined less because it’s more difficult to find.
What The Stones Are Used For
Although both epidote and zoisite are used primarily for ornamental purposes, below are the different uses of each stone.
Zoisite is used for ornamental purposes such as sculptures or religious icons.
It has been popularly used to form cabochons or beads for bracelets and necklaces when cut and polished.
Zoisite can also be carved into spheres or small figurines or figures. Zoisite is used to make a gemstone called tanzanite.
Epidote is sometimes sold in jewelry stores as a gemstone called Pistacite.
Epidotes can also be used to make ornamental carvings.
Epidote can be used as abrasive sandpaper to refine other minerals, including gold.
Some people believe epidote cures ailments of the eyes, bones, and heart, including arthritis and asthma, but there’s no evidence for this besides word of mouth and testimonials.
Where Are They Found?
Epidote is found in regions of high pressure and low temperatures.
It is commonly associated with metamorphosed limestones, schists, and gneisses.
Epidote is considered a common mineral, but Epidote crystals are not as well known to the general public as many other minerals such as pyrite or quartz.
Epidote crystals are rarer than more commonly available minerals because they are generally considered an accessory mineral in rock formations rather than a primary mineral.
Epidote deposits are found all over the world except Antarctica.
Zoisite is a calcium aluminum hydroxy sorosilicate mineral.
It crystallizes in the monoclinic system and occurs mainly in metamorphic rocks such as marble and gneiss.
Zoisite occurs in shades of green, brown, yellow, and colorless.
Ultimately, the choice to use either epidote or zoisite will depend mainly on the aesthetic you seek.
The two gems exhibit similar properties and can be used interchangeably in most cases.
On their own, both epidote and zoisite are pretty different from one another, but as part of a metamorphic rock containing minerals in layers–analyzing the chemistry of these two minerals can be especially tricky.
The only way to honestly say for sure is to look at the crystals themselves under magnification.
his has the added benefit of giving you a chance to closely examine an interesting rock formation in which these two minerals are intergrown.
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