Ever run a fingertip across the chalk-white crust inside Manitou’s Soda Springs tunnel and think, “What on earth is this stuff—and is it safe to pocket a flake for the road?” You’re not alone. From curious locals squeezing in a Saturday micro-adventure to road-tripping history buffs and Instagram-hungry campers, everyone stops to stare at those sparkling layers.
Key Takeaways
• The bright crust on the tunnel walls is dried mineral “candy” made by Manitou’s fizzy spring water.
• It is mostly baking-soda and chalk crystals, not table salt.
• White means soda or chalk, orange means iron, and light pink means manganese.
• Touching is fine, but leave big pieces so the wall can keep its sparkle.
• Bring a headlamp for the dark tunnel and gloves because the crystals feel like sandpaper.
• The loop walk from Pikes Peak RV Park is free and only about 1.5 miles.
• Drink from the outdoor fountains, not the tunnel drips; tunnel water can hold germs or too much metal.
• Shine your flashlight from the side to make the crystals shine in photos..
Stick around and we’ll decode the tunnel’s natural “wall candy” in plain English—no grad-school goggles required. You’ll learn which minerals paint the tunnel white, pink, or rusty orange, whether a quick taste is blissful or risky, and exactly how to collect a postcard-sized sample without breaking rules (or crystals). Bonus: we’ve mapped a 1.5-mile loop from your Pikes Peak RV pad, tossed in a kid-friendly chemistry trick, and flagged the best low-light photo angles.
Ready to turn a ten-minute walk into a story worth telling—and maybe testing? Let’s tunnel in.
The quick need-to-know before you step inside
The tunnel salts are not table salt. They’re mostly re-precipitated sodium bicarbonate and calcium carbonate that drifted up in Manitou’s famous mineral water, lost carbon dioxide in the open air, and crystallized on century-old drainage walls. In thumbnail amounts they’re largely harmless, but the city discourages bulk removal because thick sheets take decades to regrow. Think of them as geological lichen: fascinating to examine, fragile to the touch.
If time is tight, memorize three field facts. First, bright white crusts signal soda or calcite; orange streaks mean iron oxides; pale pink whispers hint at manganese. Second, the entire loop from Pikes Peak RV Park to the tunnel mouth and back is free and about 1.5 miles—perfect for families or a lunch-hour leg stretch. Third, bring a headlamp and gloves; the tunnel is dim, and crystals abrade skin faster than beach sand.
From limestone depths to tunnel crusts: the plain-English geologic tour
Picture a snowflake melting on Pikes Peak. That meltwater seeps through fractured limestone, absorbing carbon dioxide and becoming ever so slightly acidic. The mild acid dissolves bits of calcium, magnesium, sodium, chloride, and sulfate, turning ordinary runoff into mineral tonic. As the water is pushed upward along Rampart Range faults, pressure drops, CO₂ bubbles off, and the brew loses its ability to keep everything dissolved. Some minerals re-solidify right inside the rock pores, building subtle veins; the rest surface at Manitou’s fizzing springs or inside forgotten drainage adits beneath Manitou Avenue. You can trace that journey in more depth on the Manitou Springs Wiki.
In those dark adits the last gasp of carbon dioxide escapes, moisture evaporates, and the dissolved ions finally crash out as efflorescent crusts. Over decades, new layers stack like geological baklava: silky white soda crystals, popcorn-textured calcite, even translucent halite needles when chloride is high. The result is a shimmering mural that locals mistake for spilled plaster until a flashlight reveals microscopic prisms.
Numbers that tell the chemical story
Every spring feeding the tunnel carries a distinct signature. Cheyenne Spring roars in at calcium 440 mg/L, sodium 450 mg/L, and magnesium 90 mg/L, so its runoff often leaves thick bands of calcium carbonate beside delicate sodium bicarbonate filigree. Seven Minute Spring, leaner at calcium 303 mg/L and magnesium 83 mg/L, tends to coat walls with purer calcite that gleams snow-white under LEDs. Warm Shoshone Spring, meanwhile, is loaded with chloride and a whisper of lithium, so the rare halite needles and faint pink manganese halos you’ll spot deeper in the tunnel likely trace back to that warmer flow. Detailed wellhead stats appear on Cheyenne Spring Info.
Decoding those mg/L figures isn’t hard. Milligrams per liter equal parts per million—a handy mental conversion. Total dissolved solids below 500 ppm taste crisp; between 500 and 1 000 ppm the water feels mineral yet pleasant, and above that most palates register a saline edge. Calcium plus magnesium define hardness: under 60 ppm is soft, over 180 ppm is rock hard. Cheyenne’s 440 ppm calcium alone rockets it off the charts, which explains the milky crust it leaves on tunnel walls and the silky feel it imparts when you swirl it in a bottle.
Benefits, myths, and real risks
Long before bathhouses lined Manitou Avenue, Ute and Cheyenne peoples revered the carbonated springs for healing vapors. By the 1890s, resort doctors bottled tunnel salts and prescribed them for dyspepsia, kidney ailments, and “general ennui.” Victorian marketing aside, modern science does credit calcium and magnesium with bone and muscle support, and trace lithium may contribute to mood regulation, though doses from casual sipping remain tiny.
Risks, while minor, are worth noting. Manganese occasionally spikes high enough for state health offices to advise limiting daily gulps, particularly for infants. Recent advisories appear in this Water warning report. And remember: dried tunnel crusts are mostly insoluble—so licking flakes will add more grit than benefit. If you crave the taste, use the public fountains outside; they’re monitored and flow continuously. Save tunnel salts for the camera lens, not your snack bag.
How to walk, see, and photograph the salts
Set out from Pikes Peak RV Park’s front gate, turn right on Manitou Avenue, then left on Ruxton to sample Iron and Navajo Springs. Continue to Soda Springs Park, duck under the pavilion, and enter the drainage tunnel just west of the playground. The loop returns along Cañon Avenue and drops you back at the RV park in about 40 minutes, even with photo pauses. Cell-service junkies will appreciate full LTE along the streets, but reception drops to two bars inside the tunnel—download your map offline before you plunge in.
Crystal shots shine when late-morning sun ricochets off the creek and sneaks through the tunnel mouth. Switch your phone or DSLR to macro, steady at f/8 if possible, and rake a flashlight sideways across the crust to fire miniature rainbows. Tripod legs can skate on calcite, so plant them in gravel seams. When you share, tag #SodaCrystalsCO; the RV park reposts favorites every month, and the City’s tourism board occasionally features standout pics.
Safe sampling and leave-no-trace tips
Touching a wall? Slip on disposable nitrile gloves; crystals are abrasive and wick oil from skin faster than chalk. Instead of prying chunks, coax thumbnail-size flakes with a soft artist’s brush or plastic spoon, then drop them into a labeled zip bag. Memory fades after six stops, so jot date, time, and fountain name immediately.
For water samples, rinse an HDPE bottle three times with spring flow before the final fill, cap tight, and tuck it upright in a cooler. Test pH on site with paper strips—acidity changes during a hot car ride. The city allows tasting but prohibits commercial resale; leave slabs in place so the next traveler sees the same glittering ribbons. And always pack out gloves, bags, and used pH strips; even micro-trash dulls the tunnel’s magic.
DIY tunnel-side chemistry for all ages
Turn your camp table into a field lab with pH strips, kitchen vinegar, and a spoon. Dab vinegar on a fresh crystal: if it fizzes like seltzer, congratulations—you’ve met calcium carbonate. Drip the same vinegar on an orange streak that refuses to bubble and you’re likely staring at iron oxide. Next, test tunnel water; readings typically hover between 6.5 and 7.5. Compare that to Cheyenne Spring’s bottle you filled earlier—notice how carbonation nudges pH slightly upward.
Data-minded nomads can go deeper. Average ion counts hover around calcium 400 mg/L, sodium 300 mg/L, and chloride 200 mg/L, according to compiled USGS records linked through the city portal. Download the full CSV dataset and a concise PDF summary via the Manitou Springs hydrochemistry page, then chart your own scatter plots over campground Wi-Fi. The clubhouse router serves a solid 20 Mbps; reception at the tunnel mouth varies but usually holds two LTE bars—plenty for Instagram uploads between tests.
Guided learning, tours, and accessibility
If you prefer a deeper dive at a leisurely pace, the Manitou Heritage Center hosts a one-hour “Springs & Salts” lecture every Friday at 10 a.m. A ramp at the side entrance accommodates wheelchairs, and folding chairs mean you won’t stand the whole time. The lecture dovetails into a short walk to Iron Spring, where docents demonstrate CO₂ degassing with a simple soda-bottle trick.
Self-guided explorers can scan the QR code posted on the gazebo outside Iron Spring to launch a free audio tour. Benches crop up every 300 feet along Manitou Avenue, and public restrooms await at Soda Springs Park. Even in peak season, that infrastructure keeps the outing friendly for knee joints and grandkids alike.
Those dazzling white, pink, and rust-orange crusts aren’t just pretty—they’re a living textbook only ten minutes from your campsite. When you base yourself at Pikes Peak RV Park, your lab bench is a picnic table, your field guide is this blog, and the tunnel is your hands-on classroom. Reserve a creekside spot, stream a little geochemistry primer over our fast Wi-Fi, and wake up steps from Manitou’s most curious mineral mural. Book your stay today and turn the Soda Springs salts into the highlight of your Colorado story.
Frequently Asked Questions
Q: What minerals actually make up the white, orange, and pink crusts in the Soda Springs tunnel?
A: Lab tests on tunnel scrapings show that the bulk of the crust is sodium bicarbonate and calcium carbonate, with lesser streaks of iron oxide (rusty orange) and trace manganese oxides that sometimes blush pink; you may also spot occasional halite needles where chloride is high, but no table-salt–grade sodium chloride layers have been found in significant amounts.
Q: Are the salts safe to touch or taste?
A: Brushing a fingertip across the crystals is generally harmless, but they’re abrasive and will dry skin quickly, so lightweight gloves are smart; tasting a crumb is unlikely to hurt a healthy adult, yet the city discourages it because insoluble grit offers no nutritional value and trace manganese can exceed state guidance for infants—sip monitored fountain water instead.
Q: May I take a small flake home as a souvenir?
A: Collecting a thumbnail-size chip for personal study is tolerated, provided you loosen it gently with a plastic spoon or soft brush and leave thicker sheets intact; bulk removal, hammering, or commercial resale is prohibited under the city’s mineral‐resource ordinance, so err on the side of minimal impact and pack out all tools and bags.
Q: Is the tunnel open to the public, and how do I get there from Pikes Peak RV Park?
A: Yes—access is free, ungated, and a straight 0.75-mile walk: exit the RV park, turn right on Manitou Avenue, left on Ruxton, then dip under the Soda Springs Park pavilion where the drainage adit begins; the full out-and-back loop is 1.5 miles and takes about 40 minutes at a photo-friendly pace.
Q: How were these salts formed in the first place?
A: Rain and snowmelt percolate through Pikes Peak-area limestone, dissolving calcium, sodium, and other ions before rising along faults; when the carbonated water reaches the lower-pressure tunnel, carbon dioxide degasses, evaporation kicks in, and dissolved minerals recrystallize layer by fragile layer on the walls—essentially rock candy made by geology, not sugar.
Q: What did Indigenous peoples and early settlers think of the mineral content?
A: Ute and Cheyenne communities revered the effervescent springs for ceremonial and medicinal purposes, while late-1800s resort doctors bottled tunnel salts as tonics for digestion and “nervous ailments”; newspaper ads from 1893 even touted them as a cure for “railway fatigue,” although modern science credits only mild electrolyte benefits.
Q: Are guided tours or lectures available nearby?
A: The Manitou Heritage Center hosts a free “Springs & Salts” lecture every Friday at 10 a.m., often followed by a docent-led stroll through the tunnel; families can also scan the QR code on the Iron Spring gazebo for a self-paced audio tour, and seasonal Saturday evening “ghost-cum-geology” walks offer a flashlight perspective for night owls.
Q: What simple science experiment can kids do with a collected crystal?
A: Place a crystal on a paper plate, add a drop of kitchen vinegar, and watch for fizz—bubbling means you’ve got calcium carbonate; if nothing happens, try sprinkling a little table salt on top and shining a flashlight sideways to compare reflective habits, turning a souvenir into a quick lesson on mineral identification.
Q: Any safety precautions for getting that perfect macro photo?
A: Bring a headlamp to rake light across the wall, keep your lens cap on while moving (the dust is micro-sandpaper), and avoid leaning or bracing on the crystals themselves because they fracture easily and leave sharp edges that can slice both skin and camera straps.
Q: Can I pair the tunnel visit with a short hike or bike ride?
A: Absolutely—continue up Ruxton Avenue to catch the Iron Spring Trail for a 1-mile creekside walk, or pedal the paved Midland Trail back toward Colorado Springs; both routes start within a block of the tunnel and add less than an hour to your outing.
Q: How’s the cell service and Wi-Fi around the tunnel and at the RV park?
A: Inside the adit you’ll see one to two LTE bars on major carriers, enough for a quick Instagram story if you preload filters, while Pikes Peak RV Park’s clubhouse Wi-Fi clocks around 20 Mbps—perfect for downloading the city’s hydrochemistry CSV or uploading a photo set once you’re back at camp.
Q: Where can I find raw chemical data for my own research?
A: Downloadable spreadsheets and a concise PDF summary of ion concentrations for Cheyenne, Seven Minute, and Shoshone Springs live on the Manitou Springs hydrochemistry portal (linked in the blog post); the files include major cations, anions, and trace elements, all in parts per million, ready for spreadsheet number-crunching.
Q: Do the salts offer any proven health benefits beyond the spring water itself?
A: Apart from trace calcium and magnesium that support bone and muscle function, dried tunnel crusts deliver negligible nutrition because most compounds are insoluble; any lithium or manganese present is in amounts too low (or in the latter case, potentially high for infants) to make licking flakes worthwhile, so stick to drinking the monitored fountains for mineral intake.
Q: What should I do if I notice vandalism or missing crystal sheets?
A: Snap a quick photo, note the location, and email or call the Manitou Springs Parks Department listed on the tunnel entrance sign; prompt reporting helps staff document damage and install discreet signage or trail cameras to protect the formations for future visitors.
Q: Is the tunnel accessible year-round and wheelchair friendly?
A: The passage is open in all seasons, but winter brings thin ice films that can turn the gravel floor hazardous, so traction spikes are recommended; the grade is nearly level yet the surface is uneven and muddy at times, making it challenging for standard wheelchairs—mobility-aid users often prefer the sidewalk tour of surface springs instead.