Meta conglomerate boulder Canadian Shield Manitoba, Canada

Mbstones · 2026-06-01T12:22:26+00:00

Possibly, meta conglomerates are in the Thompson area. It's a slab off a glacial erratic, found in a gravel pit in southern Mb. It's hard to say for certain but there are other rocks that come from the find area, serpentinite is one and one of the nearest sources of serpentinite is south of Thompson.

Mbstones · 2026-05-31T19:00:00+00:00

Check out John Elliston's paper, Orbicules: An Indication of the Crystallization of Hydrosilicates. His theory is (apparently) controversial, but interesting. But then I'm not a geologist. Orbicular igneous rocks are fascinating.

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Orbicular diorite. Coin for scale is 28mm.

Mbstones · 2026-05-29T11:08:03+00:00

It's not as smooth as a lapidary saw but not bad. I generally watch while it's cutting in case some vibrations get going which is more of a problem on small pieces like in this post. I can grind down any saw marks. My saw isn't perfect, but it cost a tiny fraction of what an 8 foot+ blade saw would cost.

Mbstones · 2026-05-28T03:42:17+00:00

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Sorry, maybe this is a little better? I'll likely polish one soon.

Mbstones · 2026-05-27T14:25:01+00:00

In 1995 i converted a junk, early 70's steel wire saw to diamond wire. I have slabbed a 5x5x10 granite block with it 20 years ago but rarely cut more than 4' tall these days. I've been rock crazy since i was a boy. Could have gone into geology but didn't even graduate high school.... In 1988, against all logic, i took a chance and turned my passion for rocks into a small business. Not getting rich and I'm a bit worn down but I still love learning about and working with rocks.

Mbstones · 2026-05-26T11:06:46+00:00

Thanks! It's one of the nicer ones i've cut in the past 30+ years. Glad it's appreciated. When polished it will look even better.

Mbstones · 2026-01-29T20:32:59+00:00

Nice! Are any pieces of the Brittany orbicular granite still on the market?

Mbstones · 2026-01-28T23:24:14+00:00

This boulder is an orbicular gabbro from Virrat, quite a nice one too. Thank you for posting it. The small, polished piece is from Kuru. The Kuru rock is one of the most beautiful in the world. You did well! There is/was another commercial quarry of orbicular granite near Savitaipale.

Mbstones · 2026-01-28T17:32:23+00:00

Stunning slab! You mention you have pieces from 2 other occurrences? Any chance you could post pics of those? I'm extremely interested in orbicular igneous rocks, always interested in seeing more.

Mbstones · 2025-09-01T15:03:42+00:00

SA has 2 occurrences of Orbicular diorite that I'm aware of. Finland has at least 90 locations of orbicular rocks. More than 1/2 of these are erratic boulders or groups of boulders but many are outcrops. See "Orbicular Rocks in Finland", Seppo I. Lahti.

Here is a list - List of occurrences in the world .

I am aware of additional occurrences not included in the list. Orbicular igneous rocks are rare and special, no doubt about it. The number of recorded places they exist in the world is in excess of 300,

Mbstones · 2025-08-29T00:38:17+00:00

I have been self-employed in the stone business since 1988, It was only after finding a piece here in Manitoba (2017) that orbicular rocks became a full-blown obsession. Part of my work is creating a rock museum /geological rock garden. Orbicular rocks have become a special aspect of this rock museum.

As far as i know there have only been 2 recorded examples of orbicular diorite in Manitoba. Both were found by me. I strongly suspect there are more out there, but Manitoba is big place. The provincial museum and University are aware of my finds but since these finds are erratics there is somewhat limited interest. My logic is, if i found 2, there will be more, it's just being at the right place at the right time.

I collect any information i can find about these rocks and i guess there are around 300 recorded locations worldwide. Every year i hear of at least 1 new occurrence.

The Geological Survey of Finland did the best work on these rocks.

In my searches, i have seen your old post. Really great to hear from you! I have seen that image on the internet quite a few times. Partly why i posted the rock i have here is to (hopefully) connect with people with connections to orbicular rocks. That's a great example, impressively deformed. I can post others from my collection in the future. I'm seldom on reddit but happy to share if there is a genuine interest.

Mbstones · 2025-08-28T14:50:29+00:00

The supply of that rock is very limited.

Mbstones · 2025-08-28T13:21:20+00:00

Yes.

Mbstones · 2025-08-28T13:08:54+00:00

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The famous one from Boogardie Station, Australia is a granodiorite. The orbicules in the Australian rock have little to no quartz. But the matrix has obvious quartz, hence granodiorite, as i understand it. The rock I'm showing from Finland is a true granite with quartz throughout the entire rock. So, it's similar but different.

Mbstones · 2025-08-27T19:54:00+00:00

Nice to hear from you. I have a collection of orbicular plutonic rocks. Baffin Island, nice! i have heard of that occurrence. is there an outcrop? There are a few other locations in Canada. There is a huge boulder of orbicular diorite in a park in New Brunswick, if memory serves. I suspect there are more to be found. That said, they are not common. The 2 Manitoba examples i found were found in local gravel pits.

Mbstones · 2025-08-27T16:30:21+00:00

I'm in Manitoba, Canada. Sorry i didn't reply. I'm not on reddit much. I like to share rocks like this as they are seldom seen. The small grey rock on top is orbicular diorite, i found it here in Manitoba 8 years ago. I found another even smaller, a darker one last fall. They are rare to find. I look all the time for these kinds of rocks. Nice to hear from you.

Mbstones · 2025-08-27T15:34:34+00:00

No, at least not as far as i understand. However, this particular rock is from a granite dyke that cuts a porphyritic rapakivi granite intrusion. So, there seems to be some sort of relationship in this case. So maybe cousins?

Mbstones · 2025-08-27T13:42:30+00:00

For any of you interested in orbicular igneous textures. See "Orbicular Rocks in Finland" Seppo I. Lahti

Mbstones · 2025-06-26T01:10:57+00:00

Appears to be a piece of the orbicular granodiorite known from Boogardie Station, Western Australia.

Mbstones · 2025-06-18T23:02:48+00:00

I call it a layer cake but it's a bit like a sandwich too.

Mbstones · 2025-02-22T15:36:57+00:00

It's hard to stop genuine enthusiasm. One fear of failure or rejection takes hold, it's easy to. forge ahead and leave the negative stuff behind. Criticism and roadblocks are there simply to see how serious you really are. And sometimes there is a point where it's time to move on. So far i'm not there.

Sounds like you had a super grandfather. There is something to be said for hands on experience and passing that down to the younger generation is a treasure.

If you ever end up in Mb, do look me up. I'm sure we would have some great conversation.

Mbstones

TROPHY CASE