There are a few rocks and minerals out there that are notorious for getting mixed up with one another.
One of these easy-to-confuse pairs are feldspar and jasper.
In this article, we’re going to explain what each stone is, how they’re similar, and how to tell them apart.
Feldspar vs Jasper (Explained)
First, let’s talk about what these two minerals are.
As opposed to being one singular mineral, the name “feldspar” actually refers to a group of about 26 different minerals whose structures, chemical compositions, and physical properties are so incredibly similar that they are all grouped together.
Within the overarching classification, feldspar minerals are then grouped into two subcategories: plagioclase feldspar and potassium feldspar (also referred to as alkali feldspar).
Plagioclase feldspar contains more calcium and sodium, and a combination of albite and anorthite.
As the name implies, potassium feldspar contains more potassium.
Some examples of plagioclase feldspar include labradorite, albite, and andesine, and examples of potassium feldspar include anorthoclase, sanidine, and microcline.
Although feldspar isn’t considered the most attractive mineral, occasionally it can reach gemstone status.
Feldspar gemstones are better known as moonstones, sunstones, aventurine, and amazonite.
Outside of these few exceptions, feldspar is typically white, though it can appear in shades of blue, gray, brown, orange, pink, yellow, green, and can even be colorless.
Feldspar is used in the production of glass, ceramics, pottery, paint, and plastics.
Jasper is a variation of chalcedony, which is a variety of quartz.
In fact, jasper is among the most popular varieties of quartz and is considered a semi-precious gemstone.
All variations of quartz have the same chemical formula, silicon dioxide, but form under vastly different circumstances, which is what makes them unique.
Jasper forms when silica slowly seeps into a sedimentary material.
Over long periods of time, the silica begins to act like a glue and cause sedimentary material to stick together and harden, which becomes what we recognize as jasper.
Jasper is most commonly seen as a deep reddish-brown or yellowish.
This color comes from the original layers of sediment, and is rarely ever uniform.
Jasper contains up to twenty percent foreign materials, and these materials are what determine the colors and designs.
While other varieties of quartz are used in production, jasper is almost exclusively used as jewelry and ornamentation, like vases.
Similarities Between Feldspar and Jasper
Occasionally, feldspar and jasper are mistaken for one another because they can appear in similar colors.
They are both also silicates, which means that both of their chemical compositions include silicon.
Feldspar and jasper can also be found in similar locations and rock formations, which can lead to confusion.
However, outside of these three similarities, these two minerals have little else in common.
Differences Between Feldspar and Jasper
First and foremost, while both minerals include silicon, the main element of feldspar is actually aluminum, which makes the chemical composition of feldspar and jasper quite different.
Additionally, feldspar is a collection of minerals with incredible similarities, while jasper is a variation of quartz, which is its own individual mineral.
These are the most important distinctions; however, feldspar and jasper also differ in formation, hardness, cleavage, appearance, and gemstone classification.
Feldspar forms when magma in intrusive and extrusive rocks crystallize.
As we’ve already discussed, jasper forms when silica seeps into a rock and hardens, binding sedimentary material together.
So, while feldspar and jasper can be found in the same rocks and even look similar, they formed very differently.
If one is ever in doubt about which mineral is which, hardness is always a good indication.
On the Mohs hardness scale, feldspar rates at a 6, while jasper rates at a 7.
Therefore, if a sample of feldspar were to be struck against a sample of jasper, the jasper would remain solid while the feldspar would be scratched.
Feldspar and jasper have different crystal structures, and therefore different cleavage.
Cleavage refers to the way a mineral breaks along flat planes where they are weakest.
Feldspar has two perfect cleavages which meet at a 90-degree angle.
Therefore, when a sample of feldspar is hit with a geologist’s hammer, the pieces will be predictable and will break the same way each time it is hit.
On the other hand, jasper, like all quartz varieties, has indiscernible cleavage.
When a sample of jasper is hit with a geologist’s hammer, the pieces will have no discernable pattern and will break into different sizes and shapes each time it is hit.
A good rule of thumb is to never rely on appearance alone to determine what rock or mineral you may have.
Feldspar, while usually white, can come in all sorts of colors.
This means that it can look very similar to the grainy reddish, brownish, and yellowish colors that are most commonly attributed to jasper, though it is not common to see feldspar in these colors.
Additionally, feldspar is typically very cloudy and does not allow light to shine through clearly.
- Gemstone Classification
If a mineral has a color or pattern that people find attractive, it can be considered a gemstone.
Jasper is very popular because of its color and the patterns that develop in it, and is therefore considered a gemstone.
Feldspar does have variations that are considered gemstones, like moon and sunstones, but are not usually considered precious.
The hardness of jasper compared to the hardness of feldspar contributes to its gemstone status, as it is less easily broken or scratched.
It’s easy to confuse feldspar and jasper because they can look quite similar, both contain silicon, and are often found in the same rocks.
However, after a bit of research, it’s easy to find ways to discern which is which. First of all, you have to know that their chemical makeup is different.
After that, you just have to pay attention to how they formed, which sample is harder, how they break, how they look, and which is considered a gemstone and why.
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