There are loads of rocks and minerals – TREASURES – to see, touch and admire out there in the big wide world. 

We’ll get to some of those far-flung places, but we can’t always journey far and wide, nor do we need to. A worthy adventure always starts right where we’re at. It also reminds us of the goodness that surrounds us in the present.

So, folks, I’m starting in my own backyard to see what’s under our feet in the Central geologic region of Minnesota. 

LOCATION:

Near Buffalo, MN 

MODE OF TRANSPORTATION: 

Feet (could also be accomplished by assistive devices: chairs, walkers, etc.)

GEOLOGY:

Buffalo, Minnesota, is located in Wright County in the central part of the state. The geologic structure of Buffalo and its surrounding area is characterized by its location within the Central lowlands region of North America. It’s in a region shaped by both geological processes involving sedimentary bedrock and the more recent glacial activity that carved out its distinctive landscape, characterized by lakes, wetlands, and rolling hills. These geological factors continue to influence the area’s land use and natural features.

Available Rocks and Minerals

Let’s get clear on what we’ll be looking at with a review of some basic definitions provided by the US Geological Survey:

Mineral – A mineral is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Common minerals include quartz, feldspar, mica, amphibole, olivine, and calcite.

Rock – A rock is an aggregate of one or more minerals or a body of undifferentiated mineral matter. Common rocks include granite, basalt, limestone, and sandstone.

There are three types of rock:

• Igneous –  Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots and rises toward the surface.
  
• Metamorphic – Metamorphic rocks started out as some other type of rock but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. They form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids, or, more commonly, some combination of these factors.
  
• Sedimentary – Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth’s surface. Sedimentary rocks often have distinctive layering or bedding.
  

USGS_RocksMinerals

The geology around Buffalo, MN, primarily consists of sedimentary bedrock, which includes various common rocks and minerals typical for such geological formations. Here are some of the common rocks and minerals found in the vicinity of Buffalo, MN:

• Limestone [Sedimentary]
• Shale [Sedimentary]
• Granite [Igneous]
• Basalt [Igneous; volcanic rock that is the most common igneous rock on earth]
• Dolomite [Sedimentary carbonite]
• Sandstone [Sedimentary]
• Gneiss [Metamorphic]
• Schist [Metamorphic]
• Quartz: A common mineral found in various rock types, including sandstone. In some areas, it can also form quartz veins.
• Calcite: A common mineral often found associated with limestone and dolomite. It is a major component of these carbonate rocks.
• Glacial Deposits: gravel, sand, and clay

TREK PREP

This outing doesn’t require a lot of prep or high-end tools. I simply grab a gardening tool for light digging and a canvas bag for storing any gems I find. 

I use the Rock Identifier app on my iPhone to photograph and gather initial IDs, and in a pinch, I’ve used baskets, boxes, bags, cans, shoes, and, of course, my pockets to carry my finds. This time, I used a small fabric knapsack.

On this journey I went solo. But it’s a great activity to do with kids, visitors or neighbors, because everybody loves a treasure hunt — especially in their own backyard.

Bonus: you’re close to home for food/water/bio breaks.

Prep Tip

If I’m searching in grassy or forested areas, I wear long pants and socks and use bug spray that repels ticks and other insects. I don’t want to have adventures leading to illness.

Rarely do I forage without a hat or headscarf and a long-sleeved shirt. Just makes sense.

FINDINGS

Strolling through the edge of the woods looked like a good place to start, as there were a few small rock mounds by a fallen tree. Once I started digging, here’s what presented itself.

First, a limestone nugget about 2” x 3” poked out from under the leaves. So bright and clean, like it had been pre-washed, or sucked on by a large mammal, then spit back out.

Figure 1: MOBY – Limestone

Limestone is defined as “a sedimentary rock composed principally of calcium carbonate (calcite) or the double carbonate of calcium and magnesium (dolomite). It is commonly composed of tiny fossils, shell fragments and other fossilized debris.”

Since I have several limestone specimens already, I’ll leave this little beauty right where it lays. Like the vast majority of treasures I come across, the wonder is already of them in the place they reside. No need to move it elsewhere or make it anything else. Just appreciate the stone as it is. 

Stepping further into the woods, I discover a fellowship of mid-size rocks that all appear to be different. (Geology is nothing if not diverse.)

Since they’d all come up for air, I didn’t have to dig too deep to identify them, just brush away some debris. In addition to more limestone, there was sandstone and conglomerate stone.

Partially exposed rocks and minerals are often wider than they appear at surface. Sometimes, digging around them yields a much larger specimen than expected.

Q: So what have we Learned?
A: Like humans, initial rock appearances can be deceiving.

A side bonus of rock hounding is that the search always yields unexpected delights. On this trek, there’s beautiful soft moss covering the forest floor. A large tree, felled by a storm, provides nourishment for growing fungi, and its trunk yields a beautiful pattern that tells a story of years of growth.

Circling back to the edge of the yard, I spot the basalt stone ‘memorial’ where we buried two of our beloved feline family members over the years, Dama and Rex. They were great companions.

It’s a beautiful spot to honor them, and basalt is the perfect guardian stone, in my opinion. It’s common but elegant with a charcoal gray sheen that is only enhanced by the elements. Classic rock goodness! RIP, little ones.  

Moving out of the yard and down the trail, I hike to a county road that is under construction. The equipment has stopped for the day, and there is a lot of sediment where the old surface has been taken up. Eyeing the dirt piles, I lightly kick into the reddish-brown muck. There’s a lot of clay in this area, so it would make sense to see shale (below) as well as more of the rock types we uncovered earlier.

Figure 7: Shale – Shale: soft, finely stratified sedimentary rock that formed from consolidated mud or clay and can be split easily into fragile slabs.

Shale, sandstone and limestone are all common to this part of Minnesota, as shown in the following illustration from the University of Minnesota:

Source

I also picked up a sweet little milky quartz. A mineral that is fairly common in the area but always a joy to unearth because of its luster. That one goes in my pocket. 

And, hey, look at this! A few steps away, I walk right over a piece of granite, a local favorite and countertop must-have. In fact, the nearby city of St. Cloud is known as the ‘Granite City.” There are large quantities of granite in the area, which support numerous granite quarries.

The light is getting lower, so it’s a good time to safely head back home. 

I try to stay mindful of the time of day when taking a trek – and planning is key. It’s important to be able to see all of the areas and trails I’m exploring in good light. I don’t want to get caught in the dark, especially without proper gear in unfamiliar territory.*

A watch with a compass and/or smartphone is super helpful and, heck, essential nowadays.

*For a real-life tale of HOW NOT TO DO IT, you’ll want to read my upcoming post – Schist & Giggles – Maine Coastal Trails, where poor timing and lack of proper equipment lead to a hair-raising and potentially dangerous outing.

Today, I just need to walk back down the paved road and around the curve to home. There, I can clean and label my samples. Then, I’ll decide what to create from the types of rocks and minerals discovered on this trek.

Reviewing the day’s collection

I empty my container of rocks into the laundry room sink to clean them up. In warmer weather, I simply bring my stash to an outdoor hose. Then I can wash and leave them to air dry, making sure to pick them up later so they don’t become a tripping hazard. (Yes, that’s speaking from experience).

To clean – I use water and a soft brush or non-metal cleaning pad to remove dirt and debris so I don’t scratch the rock. If dirt is deeply embedded, I may soak it in water overnight.

NOTE: Some rocks and minerals don’t do well in water and should only be wiped clean. If I’m uncertain, I err on the side of caution until fully identified.

To identify the rock(s) – I use my online rock apps, guidebooks and existing samples from my collection.

I take pictures in good light from various angles to confirm identity and add to my online collection notes. To provide a visual of the size, I may show the sample in my hand or with a coin beside it for perspective.

If I’m uncertain about the identification, I can submit pictures to an online geology group or experts for confirmation. In some cases, I’ve needed to bring a sample directly to someone with expertise for identification (think geologists, gemologists, rock shops or groups, learning institutions, etc.). My grandma’s ‘brain stone’ is one of those examples.

With the help of mineralogists I learned that it was limestone and chalcedony composition. The ‘bubbles’ and holes (vesicles) were created by chemical reactions via the groundwater, minerals and sediment. Very cool!

Once identified, I label each sample with the: 

• Type (i.e., limestone, granite, basalt, milky quartz)
• Date found 
• Size 
• Location where the sample was collected (If I’m purchasing samples from a shop or dealer, I try to get those details included with the purchase).
• Purchase price, if applicable

To store – Generally, I use plastic or glass containers with slotted compartments for storing individual stones. Craft, tackle and toolboxes work great. Used bakeware and egg cartons can work, too. Improvise!

Cardboard boxes also work fine for storage or transportation. Just keep them dry.

To help save a few bucks (and the environment), I check out thrift stores or online sources for used containers or storage items. For soft, fragile or expensive items, I wrap them in paper or soft fabric.

I then label each container and generally organize by type of stone and/or color, and store the containers in a dry, low-traffic area.

What D’Ya Make Of It?

This piece of basalt is a great size and shape for a pendant, or maybe a brooch. When I first picked it up, it reminded me of the back of a cat, and our pet memorial for Rex and Dama. So that’s the vision I started from.

1) Sketched a cat outline in my notebook, then replicated on sterling silver sheet with the stone as a template. 2) Sawed out the silver shape on my bench pin and 3) soldered a bezel for the stone onto the cat form; 4) Found a copper sheet to attach the kitty form and serve as the pendant back. I soldered, riveted and assembled the pendant, set the stone, and polished it all to a nice sheen for completion. Here’s the final piece: front, back and holding for perspecitive (1 1/8 “ x 3” )

GRANITE

To highlight our hike – and the beautiful, sparkling surface of raw granite – I decided to create a vignette that could serve as either a pendant or a small picture

1) Layed out the initial components on brass sheet with the stone as a template. 2) Sawed out the brass frame on my bench pin and marked off the key elements with marker. 3) Pierced (sawed) the branches, plant stems and birds. 4) Soldered prongs and bezels for the stones and other elements; flame-oxidized the brass. 5) set the stones, attached some metal bits for leaves and polished for completion.

Here’s the final piece (2 1/4“ x 2 ½” ) and on a miniature frame. It captures the rocks, trees, mushrooms and moss we encountered along the way. Perfect for the mantel or side table. What a lovely memory.

And there you have this week’s creations, inspired by the places and components of our trek. 

If you’d like your own custom memento inspired by a rock or element that has meaning to you, please reach out via the comments section or email me at nancy@skinoftheearth.com.

WHAT’S NEXT?

What a windfall of wonder discovered on this trip. And that was just in our backyard! Imagine what awaits us when we venture further outward!?