c/geology-rocks

That old geologist who swore by hand lenses over digital microscopes

Back in 2018 I was doing field work near Moab and this retired guy kept telling me to ditch my digital scope for a simple 10x hand lens. I thought he was just being stubborn about new tech. But after my scope fogged up and died on a humid afternoon, I borrowed his lens and actually saw grain structures way clearer. The depth of field on those cheap plastic lenses is hard to beat for spotting quartz veins or feldspar twinning. Now I carry both but use the hand lens 9 times out of 10 for quick identifications. Has anyone else gone back to old school tools after relying on gadgets?

I was skeptical about using a hand lens in the field but now I feel naked without it

For the first few months of my intro geology class I thought the hand lens was just for show. I kept missing tiny details in outcrops like cleavage planes and small fossils. Then last week I actually used it on a granite outcrop near the river and spotted microcrystals I never would have seen otherwise. Has anyone else had a tool they wrote off at first?

Can we talk about people calling every shiny black rock obsidian?

I was at a rock swap in Tucson last weekend and saw at least five different tables selling slag glass as 'rare volcanic obsidian' for $20 a piece. It matters because new collectors are getting ripped off and it muddies the real market. How do you even start to explain conchoidal fracture to someone who just got burned?

Just read that the Appalachian Mountains are older than the Atlantic Ocean

I saw this in a geology textbook at the library. It said the mountains started forming around 480 million years ago, but the Atlantic didn't open until about 150 million years later. Does that fact mess with anyone else's sense of time?

Trying to figure out if a rock I found was jasper or chert took me three whole hours yesterday

The rock in my yard went from gray to bright orange in two days

I have this big piece of granite by my back door in Phoenix. It was always a plain gray color. Then after a heavy rain last week, I walked outside and it was completely orange. I looked it up and it's called desert varnish, and the water must have brought up iron in the rock. Has anyone else had a rock change color that fast?

My cousin keeps calling any dark shiny rock obsidian and it's driving me nuts

I mean, we were at the rock show in Tucson and he pointed at a piece of anthracite coal saying 'cool obsidian'. I tried to explain the difference in hardness and how it forms, but he just shrugged. Does anyone have a simple way to explain this stuff to people who aren't into geology?

I think the obsession with 'perfect' quartz crystals is missing the point

At a rock show in Tucson, a dealer told me a milky, fractured piece from Arkansas was 'junk' because it wasn't clear. I bought it anyway for five bucks, and the internal fractures create this amazing rainbow light show under a lamp. Doesn't a unique story in the stone beat just having a clear one?

Just dropped $80 on a proper rock hammer and it's a total game changer

I mean, I used to just grab whatever old hammer was in my dad's shed for rock hunting, idk, maybe a regular claw hammer or something. It was fine for busting open some shale, but last month I tried to get a good sample from a really tough basalt flow out near the river and I just wrecked the head on my old one. The metal chipped and it was basically useless. So I finally caved and bought a real geology hammer with a square head and a pick on the other end. The first time I used it, it went right through that basalt like nothing. The weight is balanced so much better and my hand doesn't hurt after an hour. I should have done this years ago. Has anyone else made the switch from a regular hammer and noticed a huge difference?

Heard a guy at the rock shop say 'granite is boring' and it got me fired up

I was at the local gem and mineral show in Tucson last weekend, just browsing the slabs. This guy next to me, looking at some really nice pink granite, said to his friend, 'It's just feldspar, quartz, and mica. Seen one, you've seen them all. It's boring.' I had to bite my tongue. On one hand, I get it. Granite is everywhere, from kitchen counters to park benches. It's the textbook example of an intrusive igneous rock. But on the other hand, calling it boring feels wrong. The grain size, the color variations from place to place, the specific mix of minerals... that all tells a story about how and where it cooled. My take is that common doesn't mean simple. What's your view? Is granite actually a snooze, or is there more to it than most people see?

Heard a guy at the rock shop say all granite is the same

He was telling his kid that, and it made me want to correct him right there. The granite in my yard from the Adirondacks has way more feldspar than the stuff I collected in Arizona. How do you even start to explain the basics to someone like that?

Spent three days trying to identify a weird green mineral in a granite sample from Colorado. It was just chlorite staining.

Pro tip: bring a real magnet when you're hunting for meteorites in the desert

I spent a whole day in the Mojave last month picking up what I thought were space rocks, but my cheap fridge magnet wouldn't stick to any of them. Has anyone else found a good, strong magnet that's easy to carry out there?

Picked a basic rock hammer over the fancy pick for my first field trip

Everyone in my group at the Grand Canyon said to get a geological pick for better splitting, but I went with a simple Estwing hammer instead (it just felt right in my hand). I ended up being way more careful with my samples and didn't break a single one, while two people snapped their finds trying to use the pick's point. Is the pick really the better tool for a beginner, or is the basic hammer underrated?

This older guy at a rest stop near Sedona showed me a trick for spotting jasper

He was just sitting there with a pile of rocks, and when I asked, he said 'look for the waxy shine, not just the color.' He picked up a plain looking brown one and sure enough, it had that greasy luster. Anyone know other easy tells for common stones like that?

Shoutout to the park ranger who saw me trying to identify a rock with a magnet

I was at Joshua Tree last month, holding a magnet to a piece of basalt like it was a magic wand. The ranger walked over and said, 'That only works for magnetite, friend.' I'd been doing it for years on every dark rock I found. Turns out I was basically checking if my car keys were metal. Anyone else have a basic field test they were using totally wrong?

My whole rock tumbler setup just gave out halfway through polishing a batch of Lake Superior agates.

It was on the final grit stage, too. The motor made this sad grinding noise and quit. I opened it up and the belt had completely shredded. Had to finish everything by hand with a cloth and cerium oxide, which took about three hours. Anyone know a good replacement motor that can handle running for weeks at a time?

Went back to the same creek in Colorado after a big storm and the bank was totally different

The flood moved about 20 feet of soil and rock in one night, completely changing the shape. Has anyone else seen a spot change that fast from weather?

My kid asked why the river rocks in our yard were all smooth and it made me rethink erosion.

PSA: I was calling every dark rock 'basalt' for years until a trip to the Grand Canyon

A park ranger there pointed out a specific layer of the Vishnu Schist and asked me to describe it. I said 'dark volcanic rock' and she just smiled. She explained the difference between metamorphic and igneous textures on the spot, using a hand lens on a piece I had picked up. How many other basic rock types am I probably mixing up without realizing?

Hot take: The basalt columns at Devil's Postpile aren't as perfect as the guidebooks say

I was at Devil's Postpile National Monument last month, and everyone talks about the columns like they're this flawless example of columnar jointing. But when you get up close, a lot of them are really broken up and weathered. The main cliff face looks great from a distance, but walk around the base and you'll see piles of talus and fractured pieces everywhere. It made me think we over-hype these famous sites and ignore how dynamic erosion really is. The park sign says the columns are about 100,000 years old, and it shows. They're not a clean, textbook diagram; they're a work in progress. I left feeling like the messy, broken parts tell a more honest story than the perfect postcard shot. Has anyone else had that feeling at a famous geologic site, where the reality was more complex than the hype?

Why does nobody talk about using a cheap tile saw for trimming agates in Tucson?

I was cutting a big plume agate at the Tucson Gem Show and my old slab saw blade chipped the edge, so I borrowed a buddy's $90 tile saw from Harbor Freight and it gave me a cleaner, faster cut on the smaller pieces.

I finally chose a granite countertop over quartz for my kitchen

Everyone in the Reno subreddit said quartz was the only way to go because it's 'maintenance free.' I picked a specific granite called 'Ubatuba' because I love the natural sparkle and no two slabs are the same. After sealing it myself with a $40 kit, it's held up perfectly for over two years with zero stains. Does anyone else think the push for engineered stone makes people miss out on cool natural geology in their own home?

Just learned that the largest single crystal ever found is a beryl from Madagascar over 18 meters long.

I was reading a geology textbook from the 70s in my local library and found that fact on page 213, which seems wild for something that grew underground.

Can we talk about using a cheap rock hammer versus a proper Estwing for splitting granite in the field?

After breaking two $15 hammers last month trying to get a decent sample from the Barre granite quarry, I finally caved and bought the Estwing, and it went through the same rock in three clean strikes without even chipping.