c/geology-rocks

Had to choose between a sledgehammer and a chisel for splitting this big chunk of basalt

Shoutout to that geologist at Crater Lake who called me out on my hammer swing

He watched me take a swing at a basalt column and said 'you're gonna lose a finger with that form, son'. Changed my whole grip angle that day and I haven't chipped a hammer since... anyone else get schooled by an old timer in the field?

That 'easy' selenite tower I tried to polish ended up a crumbly mess on my kitchen floor

Found a chunk of green quartzite in a creek bed yesterday

I was poking around a dried-up creek near Moab after a rain and this fist-sized chunk of green quartzite caught the sun just right from under some gravel. An old guy who was also out there came over and said 'that stuff gets its color from chromium, same as emeralds,' which totally blew my small mind. Does anyone else keep random rocks on their desk just because they remind you of a specific day or place?

After 10 years I just found out I've been using my rock hammer totally wrong, a guy at the Grand Canyon pointed out I was hitting the rock at the wrong angle and chipping off layers instead of splitting it clean.

I was cracking geodes in my backyard for years thinking the jagged edges were normal until that ranger showed me one perfect whack and it opened like a book, has anyone else had a tool epiphany that embarrassed them?

Went to Carlsbad Caverns last month and the formations looked different than I remembered

I visited Carlsbad Caverns back in 2010 and then again last month, and I swear the stalagmites near the entrance look more dull and gray now. They used to have this shiny, wet look to them, but now half of them seem dried out or covered in dust. I asked a ranger about it and he said visitor traffic and humidity changes over the years can affect the surface, but he didn't seem too worried. Is that normal for caves with heavy foot traffic, or am I just imagining things? Has anyone else noticed stuff like that at other national parks?

Found out garnet sand is way tougher than I thought

I was reading a paper from the US Geological Survey and it said garnet sand has a hardness of 7.5 on the Mohs scale. That puts it right up there with quartz. I always figured garnets were just pretty red rocks for jewelry, but they actually get crushed up and used for waterjet cutting and sandblasting. Has anyone else been surprised by what a common mineral can do?

That trick with vinegar on limestone worked better than I expected

Saw a guy on a trail in Missouri mention he uses a 50/50 water and vinegar mix to clean buildup off limestone samples. Tried it on a chunk I found near the Ozarks and it took off that white crust without damaging the surface. Anybody got other cleaning tips for sedimentary rock?

Shell hunting on the Gulf coast cost me $300 in sand dollars I regret buying

Picked up a bag of so-called 'natural' sand dollars from a vendor in Destin for $300 only to find out after boiling them at home that they were just dyed concrete casts, has anyone else gotten burned by tourist trap fossil sellers?

Took me 2 years to admit I was wrong about quartz vs granite countertops

Honestly, I was a hardcore granite fan forever. I thought quartz looked fake and plastic like a cheap laminate. Then my sister got quartz put in her kitchen in Denver last month and I saw it in person. The color was way more natural than I expected, like a soft gray with tiny speckles. She spilled red wine on it and it didn't stain at all, which my granite definitely would have. I spent 3 hours at a stone yard last weekend looking at slabs and now I'm leaning toward quartz for my own remodel. Has anyone else switched sides on this debate after seeing stuff in real life?

TIL a lesson about shale the hard way on a hike near Boulder

I was out collecting samples near the Flatirons last fall, and I grabbed a nice looking piece of dark shale from a slope. I put it in my backpack with some other rocks. By the time I got back to my truck, the shale had completely broken down into tiny pieces from the jostling. It made a total mess of clay dust all over my gear. I didn't realize how fragile some sedimentary rock could be until that moment. How do you folks safely pack out fragile specimens like that?

My dog found a weird rock in the backyard that turned out to be a fossil

My beagle, Baxter, dug up this heavy, bumpy rock near our fence in Boise. I thought it was just a weird stone, but after cleaning it off, I saw a clear spiral pattern. I posted a picture on a local rockhound forum and a guy named Carl told me it's a gastropod fossil, probably from the Glenns Ferry Formation. Has anyone else found fossils in their own yard like that?

Spent two hours trying to convince a client that the 'crystals' in their basement wall were just efflorescence, not a secret quartz vein.

I had to bring in a bottle of vinegar and watch it fizz on the salt crust before they finally believed me, which honestly felt like a weird science fair project gone wrong. Anyone else ever have to do a full chemistry demo just to explain basic weathering?

Unpopular opinion: a chat with a park ranger in Zion changed my mind about obsidian

I was hiking the Narrows trail last fall and got talking to a ranger at the visitor center... I always thought obsidian was just a cool, sharp black glass. But she said, "You know, most people fixate on the color, but the real story is in the flow lines and how fast it cooled." She showed me a piece with these tiny, almost invisible bands you could only see in the sun. It made me realize I'd been ignoring the formation process and just collecting pretty rocks. I've spent the past 6 months re-examining my whole collection with a hand lens. Anyone else have a basic rock fact that totally shifted how you look at specimens?

Finally got the hang of my rock saw after a year of bad cuts

I was always getting jagged breaks on my agate slabs until I watched a guy at the Tucson gem show last month. He was using way less pressure and letting the blade do the work. I tried it on a piece of Lake Superior agate yesterday and the cut was perfect. Anyone else take way too long to figure out a basic tool trick?

Warning: Trying to identify a weird concretion from a creek bed near Boise took me 4 hours yesterday

I dropped a piece of granite in my kitchen sink and it didn't chip

Honestly, I was moving a sample from a countertop place last week and it slipped. It was a small piece, about 3 inches square, of that black granite with the big sparkly bits. I braced for a crack or a big chip in my porcelain sink, but it just made a loud clunk and was fine. It got me reading about how granite forms under huge pressure over millions of years, which makes it so tough. Tbh, I always thought it was kinda fragile like glass. Anyone else had a rock do something that totally surprised them?

My kid asked me why some rocks are smooth and some are sharp, and it made me realize I don't just point at cool rocks anymore, I actually try to explain them.

I was looking at a piece of river-tumbled quartzite from Lake Michigan with him last weekend, and I caught myself talking about transport distance and hardness instead of just saying 'that's a neat one'.

My professor said to always check the cleavage on a sample, and I finally get why

He told me last semester, 'If you don't look at the way it breaks, you're just guessing at the mineral.' I was trying to ID a piece of calcite from a site in Kentucky and kept thinking it was quartz until I saw the perfect rhombohedral cleavage. How many times have you guys skipped that step and gotten it wrong?

A sudden rock slide in the Smokies made me triple check my footing now.

I was collecting samples near a ridge in Tennessee when a small shelf gave way, sending a pile of shale down the slope about ten feet from me, so now I always look for loose material and test the ground before stepping close to any outcrop.

I was ready to give up on identifying this weird green mineral

Spent three days trying to match it to online photos with no luck. Finally, I just put a drop of vinegar on it. It fizzed like crazy, which meant it was a carbonate. That one stupid kitchen trick narrowed it down from like fifty possibilities to maybe three. Ended up being malachite, which made total sense given the location. Anyone know other simple home tests that actually work for basic mineral ID?

Found out the oldest rock on Earth is in Canada and it's over 4 billion years old

I was reading an old geology textbook from the library and it said the Acasta Gneiss in the Northwest Territories is about 4.03 billion years old. That number just stuck in my head. I always figured the oldest stuff was way younger. Makes you think about how much the planet has changed since that rock first formed. Anyone know of a good documentary that shows that area?

Rant: my whole week got wrecked by a stubborn piece of granite

Last week I was helping a buddy build a patio in his backyard, and we hit a huge slab of granite about two feet down. We thought it was just a big rock, but it was part of a solid ledge. I mean, we tried everything. We rented a jackhammer for a day, which cost us $85, and it barely made a dent. My arms were shaking for hours. After three days of this, we had to call a local guy with a mini excavator, which set the whole project back. It just stood out because I've dug up plenty of river rock and shale before, but this granite was like concrete. It really showed me how different rock types can totally change a simple job. Has anyone else had a project completely stalled by the wrong kind of bedrock?

Remember when you could just pick up a decent piece of petrified wood on the ground?

About ten years back, I spent a week in the Petrified Forest and the ground was littered with small, colorful pieces. I filled a whole coffee can with them for my niece. Went back last fall and you have to walk for miles to find even a tiny chip, and the park rangers watch you like a hawk. It feels like the easy finds are just gone now. Anyone else notice their old collecting spots are totally picked over?

Showerthought: I just hit my 500th rock sample logged in the field book

It was a piece of banded iron formation from the Marquette Range. I started this log three years ago as a grad student, just jotting down basic notes. Seeing that number made me realize how much my eye for detail has changed since entry one, which was a generic granite from a local quarry. Has anyone else had a simple count show them their own progress like that?