Silkstone Rock: All You Need To Know 

Silkstone Rock is a very rare but pretty gemstone found mostly in the region of the Cuyuna Iron Range in Minnesota and as a groundwater aquifer in the area around Pennine in Great Britain.

It glistens in a similar manner as Tiger’s Eye but has rough, fibrous areas of quartz.

Because of its extreme rarity, thorough and detailed information is difficult to come by.

Therefore, the following is all that’s available about Silkstone to the public online short of going to the library or your local lapidary club.

What Is Silkstone Rock?

From what one can learn about this stone, Silkstone is basically another form of quartz as a chalcedony and has a chemical formula of SiO2.

Also called Binghamite and Cuyunite, it crosses the bridge of several types of stones that include Jasper, Agate, Onyx, Sandstone and others.

Where Do You Find Silkstone Rock?

Silkstone comes from Minnesota around the area of Lake Superior, specifically at the Arco Mine and other areas around the Cuyuna Iron Range.

However, it also hails from several areas around the UK, specifically Great Britain from the east Pennine coalfield.

How Do You Identify Silkstone Rock?

Silkstone has a beautiful surface that’s silky smooth with a satin finish.

There is often banding that can range between brown, black, gray and white to red, yellow, grayish blue, grayish green or a combination of all of these.

It has a multi-layered structure like an agate but it sits at 4 on the Mohs scale of hardness.

The appearance is very opaque but it has a certain amount of chatoyancy like a Tiger’s Eye.

However, the chatoyancy has visible waviness.

It’s definitely coarse with the possibility of containing asbestos.

UK Silkstone

However, this describes ones you can find in the Cuyuna Range in Minnesota.

There’s a bit of difference when it comes to the ones you can find in the UK.

Formed in a delta plain environment amid water, it occupies an area 194 feet (50 meters) thick with a width of just over nine miles (15 kilometers).

The Silkstone there comprises multilayered channels of sandstone in limestone and basalt.

It has a high content of coal ash, which indicates regional peat accumulation.

This particular Sandstone channel has differential compaction.

The mineral make up helps store and transmit groundwater via the stone’s pore space, weathered zones and fractures.

This means that the Silkstone here acts as a natural aquifer.

Can You Confuse Silkstone Rock with Other Materials?

One main material that most people can confuse Silkstone with is Binghamite.

In the Cuyuna Range of Minnesota, Binghamite is in the same location as Silkstone and surrounded by heavy iron deposits.

This is a little more prevalent than Silkstone as well.

Binghamite vs. Silkstone

This means both stones are going to have a red tinge to their appearance, but Binghamite will have reds that are more obvious.

However, Silkstone’s fibers are not nearly as straight, in which quartz entirely replaces these fibers.

The fibers are coarser and the red won’t be nearly as pronounced as in Binhamite.

Binghamite is also harder than Silkstone, sitting at 5.5 to 7 on the Mohs Scale of Hardness.

Therefore, if you can use a piece of sharp glass, it will scratch into Silkstone but not Binghamite.

While it technically is an agate, the heavy concentration of quartz that replaces the fibers seen in Binghamite makes is less strong.


But, the differences can be difficult to pinpoint, therefore people have begun calling both Cuyunite.

It wasn’t until the late 1940s or early 1950s that Ray Lulling, a rock hound from Minnesota, noticed there was a poignant difference between Binghamite and Silkstone in the area.

What makes this even more confusing is the fact that both Binghamite and Silkstone take on the characteristics of Lake Superior Agate.

It has the same coloring and banding but it doesn’t have the chatoyancy as Binghamite and Silkstone.

For What Do You Use Silkstone Rock?

Silkstone is a popular gemstone for jewelry and creating intaglios and cameos.

It’s softness makes it very workable for negative reliefs and raised images.

The Romans were notorious for fashioning chalcedony, specifically onyx, in this way (called glyptography).

So, it’s ideal for things like necklaces, pendants, rings and earrings.

Please note that there’s also an architectural material on the market sold as “Silkstone.”

This is not the same thing.

This is a manmade composite similar to porcelain.

They use it for countertops, sinks, tubs and toilets as well as for tiling.

It doesn’t contain real Silkstone in any capacity whatsoever.

How Do You Care For and Polish Silkstone?

If you have a cleaned and polished Silkstone, you can keep it clean with cool water and a very mild hand soap.

Do not use dish soap, it’s far too harsh.

Dry the surface with a microfiber towel and allow it to air dry for a few hours before using or wearing it.

Simply use a soft cloth to polish up the surface.

Never use any harsh chemicals or detergents as these can alter the color of the stone.

This is also true for ultrasonic cleaners and steamers.

Do not let it sit in direct sunlight for too long, this will cause the colors and chatoyancy to fade.

What Is the Meaning of Silkstone Rock?

Silkstone is a gemstone that is thought by some to have nurturing and healing qualities.

Believers use it to try and enhance one’s patience and promote clear thinking as well as self-control and inner tranquility.

The view of the chatoyancy is considered by some to be calming, giving reassurance in times of uncertainty and worry.

It is thought to have the potential to bring tranquility to the heart.


Silkstone is a beautiful mineral that shimmers and glistens just like a Tiger’s Eye.

Indeed, some people will refer to it as “American Tiger’s Eye” to help differentiate it from the African kind.

But then again, it could just be Binghamite.

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silkstone rock