Rare Pink Dolomite

Found this specimen while hiking the rocky 2.6 mile trail at Valley View Natural Area, in Jefferson County, 2 miles south of Morse Mill. It's one of the two areas in Jefferson County where dolomite glades, or rocky outcroppings, often south-facing and hot and dry, are preserved with controlled burns and cedar-tree removal -- the only way to preserve this once-common and precious Missouri natural feature. Glades support wildflowers and wildlife that thrive nowhere else (and are prettiest in spring). Cedar trees are invasives which entered the area along with mass settlement about 150 years ago, and they overtake glades and native oak-hickory forests unless they are stopped.

But we were speaking of dolomite. Even geologists don't agree on what it is, except that it's calcium and magnesium somehow mixed, and rarely there are pink examples of it, probably from being mixed with a little iron. A dryer-sized chunk of petrified mud had this chip broken off of it, revealing lovely sparkling stone bubbles (saddles) and glittering crystals.

I learned today that flipping flat rocks looking for creatures or fossils underneath them -- and not replacing them-- destroys the flora and fauna that lived in that environment. I was never in the habit of flipping rocks but now I know for certain that it's bad manners.

The Old Tiff Mills

Interviewed a lady named Mary Jean Daugherty who grew up during World War II in Richwoods, in Washington County, next county over from here. She said, "We lived around the tiff mills, that’s what kept Richwoods going."

Q:  Around the what?

A: Tiff, white tiff, that’s what kept Richwoods going.

Q: What is tiff?

A: It’s white rock. I don’t know what they do with it, but we had big trucks come in and haul it out, and they did go dig in the forest. There was a good five mills in Richwoods; that’s what kept the town going.

I Googled "tiff mills" with no results. So I hunted up this bit of Missouri mining history. "Tiff" is a local name for the mineral barite, and Washington County just south of Richwoods had the richest barite deposits in Missouri, and companies tore up the woods to get at it.

Although barely harder than a fingernail, barite will not dissolve in water and is so dense that it sinks through mud and is impervious to radiation. It is the chalky substance in the “barium milkshake” used to diagnose digestive problems, and an ingredient in concrete and important to oil drilling. Ultimately the Missouri tiff mining companies dug up 13 million tons, and after the war found bigger deposits overseas.

The photo at the top is labeled "Tiff Mill, Mineral Point", a tiny town just northeast of Potosi in Washington County. You also see barite from my Missouri mineral collection. When bonded with sand, barite can form "roses" or "desert roses," a geological novelty item. My barite is more of a rosebud, but thought you'd like to see it.

Waterfall #3

This waterfall is just a few yards above Waterfall #1.

Fossil Fields

The bed of the mighty LaBarque Creek is a motherlode of fossils and a rockhound's Eden. The rocks are a perfect Chex Mix of limestone, sandstone, shale, chert (sometimes resembles arrowheads!), dolomite, hunks of iron, hardened clay, and marble. I find that the rocks with fossils are almost always turned fossil side up. Most fossils here are those of ancient marine plants, both simple and leafy, and simple animals, sort of like coral, called crinoids. My guess is that what you see in the close-up photo is crinoids. I don't know how or why I sleep when there is such cool stuff not 200 feet from my door.

Backwoods Beachfront

You wouldn't know by looking, but this house was once a beachfront house, and it's sitting on a fortune.

Aeons ago a shallow lake covered the Midwest, and of course it had a beach. Its sand got weathered by wind, not water. The result was a vein of 99 percent pure white St. Peters silica sandstone, five miles wide, running from Minnesota down to to Missouri. My house perches right on it.

The cliff got detonated for road widening in 2002. Where it's been in the open air for some years, oxidation and water has turned the sandstone gray or red. Not far away there's a silica mine. In 50-lb. bags the old beachfront goes to make glass, chinaware, white paint, municipal water filters, and, coarse-ground, it's sold to make sand traps on golf courses. I like it just the way millions of years have left it.