The Mirabilite Spring Mounds at The Great Salt Lake State Park

Two winters ago a Park Ranger at the Great Salt Lake State Park noticed something unusual happening along the shores of the Great Salt Lake while she was providing tours. She noticed a mound of salt appeared to be growing. She thought, well, normally minerals do not grow, so she started watching and documenting, reaching out to people. Turns out she discovered a very, very rare phenomena that has only been observed a few places around the world. Mirabilite Spring Mounds. We had had a particularly wet year that year so they thought it was a fluke. However, since they were first observed, they came back again last winter and again this winter. I find them to be absolutely fascinating so I keep coming out to see them while I can. This year they are phenomenal!

Quick Details:

Length: Its only about a half mile out and back, plus whatever wandering you do.
Trail Type: Out and back.
Difficulty: DR3. It is beach sand, and there is a small hill, but otherwise flat.
Elevation Gain: About 30 feet.
Restroom: Yes.
Dogs? Yes, leashed. But keep an eye on them so they are not damaging the fragile formations.
Other Info: Fee area. $5.00 per car. Waterproof boots highly recommended. The first year involved a lot more wading since the lake was higher.

To Get Here:

Take i80 to exit 104. Head north. Turn left in front of Saltair. Continue down the narrow rd to the fee station.

The mounds are on Silver Sands Beach, behind the visitor center.

Heading west on i80 we passed a rather large herd of Antelope (Passenger Seat Photography (PSP)). I hope all the new buildings they are putting up in here don’t chase them off.

Saltair (PSP).

The Trail:

First I just want to say: Watch your step. Avoid walking on these fragile formations. Second, not only is it illegal to take a sample, it’s pointless to. When the mirabilite gets up in temperature it breaks down to a powder called thenardite. Which isn't particularly interesting at all.

The Kennecott Smelter Stack. Tallest structure west of the Mississippi.

Before long we reached the mounds. Yay!

I just love the terraces they build. Very similar to what you see at Mammoth Hot Springs in Yellowstone, except its cold instead of hot.

We kind of made a haphazard clockwise loop to see the other mounds.

Colorful terraces on this mound.

Middle of the same mound. It seems the main spring has dried up, but it has a new spring to south.

Cropped image to see the crystals a little more clearly.

A quick overview of what is going on here. There is a layer of mirabilite (a type of salt) underground here. There are some natural springs coming up and bringing the mirabilite up to the surface. The cold weather is allowing it to crystalize and form these terraces. Once it warms up the mirabilite will break down into a powder called thenardite that is definitely not as interesting. So quick note, even if it were not illegal to take a sample, there isn’t a point to it. It will not hold it’s shape. I went into a little more depth from our first visit.

Zoomed out again.

A couple more mounds. The GSL SP page says there are 15 mounds right now, the most they have ever had. That matches my count too. The previous years there were only 3 to 4 mounds.

Little salty volcanos.

Closeup of some of the crystals.

Another mound.

Crystals.

More terraces. This is probably the most exciting mound right now.

Detail.

Crystals again.

Leetle one.

We counted at least 6 springs on this mound.

The crystals again. This is what I have become used to seeing during my previous 4 visits. We are about to see a bit of a surprise.

Another mound.

Holy crap!!!! Look at the size of those crystals!

Another angle.

Another.

Huge crystals! Okay, the previous mound wins for most interesting terrace. This one wins for biggest crystals.

This is probably my favorite mound for today.

Closer to the giant crystals. I should have tried to reach my hand out to show a size comparison.

Another leetle one.

This one is interesting.

Another angle.

Another little one.

Crystals, the size I am used to seeing.

I really just love these natural formations!

More crystals.

Another littlun.

So many mounds to explore!

More crystals.

Wetter to the south as well. That is kind of interesting. You would think the newer spring reroutes would be downhill instead of up.

This was the next coolest mound of the day.

Because it also had a giant freaking crystal!

So neat!

Closer again.

Another mound.

Closer.

Another smaller mound.

From above.

Flatter mound.

Crystals.

The mound again.

I don’t know what exactly causes the green color, but it can be pretty.

After we did our haphazard round, mom decided she was done tromping through the mud and water. The others decided to hang back with her while I did another round. Even with the mud tromping, and the small hill, she said she had a great time with us, and really enjoyed seeing the mounds, so I am glad I dragged her out today. Most of our weekly adventures are a bit much for her.

Round 2.

They are all starting to blend together, but I think this is the first, or furthest south mound again, or no, its the next one.

Crystals.

Terraces.

Another formation.

I kind of just wandered all over the place this round.

Fun mound.

The one with the big crystals again.

Most of it.

Bigger one.

The other one with big crystals.

Closer view.

Different angle.

Terraces.

Crystals.

This is the largest mound at the moment.

Panoramic.

More crystals.

Another panoramic.

Crystals.

Then I think I tried to get a picture of all of the different mounds.

The mound with the big crystals again.

Another fun mound.

Little one.

Neat mound.

Another smaller one.

Flatter mound.

The other mound with the big crystal.

Saltair.

Antelope Island. 

Another mound.

Another.

A bigger one.

Another little one.

Another mound.

I kept finding myself drawn back to this one.

Mounds in the distance.

The Kennecott smelter stack again.

Different mounds.

Panoramic of all of the mounds.

Closer look.

While we were exploring the mounds we were all trying to figure out what this big red thing was. We concluded maybe a boat, or a jet ski… turns out it was a lady in a really big red puffy dress. It made us laugh when we got close enough to really identify it, when we were so so wrong before.

Antelope Island again.

I always go a little overboard with the pictures when we come to see the mounds. They are just so fascinating! Not to mention a rare natural phenomena. Also, there were so many mounds this time! Wow! So far it hasn’t made the news this year so it wasn’t too busy. 10 out of 10 squirrels.

As for difficulty, it was mostly flat with a short steeper hill.

Dogs are technically allowed, leashed. But I wouldn’t bring them myself for fear of them damaging the fragile formations.