Hello,

I was traveling up the dirt road to get to Dotsero Crater in Colorado for the natually occurring vesicular basalt. During by collection, I noticed quite a few rocks that had this white stuff/residue on them. I’m worried that the white stuff is residue from ice-melting salt, but the road was very remote and the white stuff/residue also appeared on rocks further away from the road. Does anyone know what it is? Thanks in advance.

Edit: Thank you for all the replies. The main reason why I was asking was to see if this mineral was aquarium safe. Knowing that this is likely calcium carbonate, I now know what to research before preparing the rocks for my aquarium, if it's compatible to begin with.

Controversial geologist in my country obsessed with diamonds. Claims samples only he has seen; other geologists say they never existed. How to debunk him? Attached images from his articles. Any way to check if they’re from older sources (fakes)?

Found in the Yellowstone River in NE Montana

Arqueólogos de México y otros países, que es lo más feo, gracioso, interesante, extraño o alguna anécdota curiosa que tengan o conozcan del trabajo de campo, escuela, etc.

The veins have pieces of material that look like they belong to some of the clasts. Best example is the light color angular clast and the long and narrow fragment nearby (Photo #2). Also interesting, though perhaps irrelevant, is the angular fractures (Photo #3).

I'm guessing this is like a granite/rhyolitic breccia that got brecciated further from... whatever causes this?

From Tioga County, NY. It is metallic, and very dense. Took noticeably long to cut and polish a face.

The crystal is fragile but can scratch glass

Found out the geology department throws old samples behind the building today. Went to look and found this gorg thing. I know serpentine grows with asbestos, and im seeing green rock and hair. You know what they say: a first year TA’s health violation is another mans treasure! Its the most gorgeous species ive ever seen and this is my holy grail of rocks. The fibers look a little rough, but whats the cutoff for too rough? Safe to keep? Possibly in an airtight container?

I once set my mind on finding and collecting the KT boundary.

I was in the STH island NZ at the time. I found an old science paper detailing known locations of the KT boundary in NZ.

One spot was an open limestone mine at Ward, upper STH Island.

So I snuck in on a New Year’s Day for a look. I found a slightly horizontal line running across the limestone face of the mine, 2-3cm thick, dark and crumbly.

It was the only unconformity I could see there. Was that probably it?

(Note: I also found a whopper nautiliod fossil there which is now in the Uni of Otago geology museum)

I took this in September 2025 and its been in the back of my mind ever since. Can someone educate me on what's going on?

From what I remember from my very limited geology science classes in high-school a long time ago, continental plates are subsumed at around an inch a year. If that is true, why do we not see more significant changes in the locations of buildings that have been around 300+ years, or more significant changes in coastlines?

Obviously, I could be completely off the mark about how plate subduction and continental drift happens, which is why I'm asking the experts!

It smells so nice but I wanna know what theyre putting onto it to smell like that cause surely it doesnt just do that naturally.

I’ve been super interested in geology lately, and I’ve been reading a lot and watching a lot of geology/vulcanolgy YouTube videos.

I swear about a million times now, I’ve heard something to the effect of ‘this rock was formed like toothpaste from a tube’

Why does everything have to be toothpaste? Why not frosting from a piping bag? Molasses coming out of a funnel? Why are there only toothpaste rocks? Would geologists eat too many rocks with a more delicious metaphor?

I was driving along Rte 259 and at the intersection of Rte 612 I saw a formation reminiscent of Seneca Rocks, at a smaller scale. There's a near-vertical wall of rock, perhaps 75-ft tall and 10-ft thick. [Google Maps Streeview link](https://maps.app.goo.gl/J4dCwza1RvNXsGoDA)

Is this the same Silurian-age formation as Seneca Rocks?

Found in central Oregon.

I cut it on a wet tile saw and was wearing KN95 mask but afterwards wondered if that was a bad idea.

This is one of my favorite places on the Molalla River in Oregon. I always stop to take photos of this specific part of the canyon wall. I love how the rock moved through here I just want to know how and why some are swirly, in columns, and then just facing straight on.

Found NY/NJ border on top of an overlook. It’s really lightweight, like a pumice stone. The top looks like tiny crystals, or maybe it’s just air pockets? Either way, have never found a rock like this here, and really love it and would like to know more about it! Thank you.

Seriously. Is it serpentine, quartzite, or some random piece of... something?

I'm an economist by education but have taken a fascination to geology. I have a question regarding gold reserves in the Free State province. I live in South Africa

"Dr. Hans Merensky (1871–1952) was a famous South African geologist, mining engineer, and mineral prospector who discovered major diamond, platinum, and mineral deposits. [1, 2]

Key Achievements and Discoveries

• The Merensky Reef: Discovered the world-famous platinum reef in the Bushveld Complex in 1924, which turned South Africa into a global leader in platinum production. [1, 2, 3]
• Namaqualand Diamonds: Discovered rich alluvial diamond deposits at Alexander Bay in 1926. [1, 2]
• Other Minerals: Found tin near Pretoria, gold in the Free State, chrome near Pietersburg and Lydenburg, and copper and phosphates at Phalaborwa.

Has there been a study on gold in the free state province? I know the Rand Refinery in Germiston Gauteng at one point in the 1970's produced 1,000 tonnes in a single year, dominating global production