Up Massachusetts, as a kid, I used to find slabs of mica half an inch thick and big as your hand. That's the area, New England (and other states) where rocks are everywhere from when the glaciers melted .
Ziggy that explanation is very interesting. While the "silver mines" where the rock fossil was located in a mining town in the state of Nevada is a land- locked state miles from the ocean. Geologists refer to deposits that seen in above example pictured are the fossilized remnants of ancient coral reefs which are well-documented in the limestone strata where silver mining has taken place. It weighs over 500 pounds at 3’x2’x2’ in size. The silver mines in the state of Nevada were uniquely mined in that area found near huge sandstone quarries. The sandstone rock was formed in an ancient inland sea where marine life, including corals, left behind as fossils which were part of the "reefs" of sandstone being mined for silver in the 1950’s and 1960’s where my father managed the silver mines during that time.
Ta Pac The hydrothermal veins come up through the country rock so may well have gone through old coral reefs. When I enlarged your second picture it looks more like igneous crystals rather than a calcite replacement of a coral. Can you scratch the crystals easily with a steel knife? Calcite is 3 on the hardness scale and quartz is 7 (steel is 6.5)
Zigs sorry it;s a bit way wet and cold to go out and scrape the area as it has deep fissures , section intertwining and not easy to clear enough moss off at this time. And it is as hard as steel and weighs over 500 pounds it took a fork lift to place it on site. But.. here are a few close up pics from last season that might help. If you look closely you can see the top of the fossilized area will have grooves or lines radiating out from the axis point at the center of the bottom at ground level. Ziggy since your a huge rock enthusiast I thought you might enjoy a few of these ….
Zigs quote ; Sounds like you had an Austrocylindropuntia subulata, they grow a foot a year and are like girt spiked sausages . The fast growing huge spikey cacti was more like a cross between a 3” spikes on stems with opuntia sized huge thick rounded leaves more like a Succulent. It’s not Austrocylindropuntia subulata. It’s not that cacti it’s too small . This cacti/succulent grew over 8 feet tall and was so top heavy with rounded leaves similar to opuntia’s on rounded stems/trunk's 3-4” think with 3” long spikes. I had cut the tops off yearly and popped them in the same pot to help contain its size. It had growing spurts faster than a teen in high school. No joke trying to move that bugger outside onto a covered patio for summers you put your life at risk . Considering the long sharp spikes on the stems and smaller spikes on leaves. It only could survive approx.- indirect light in full shade in temps above 60F. It was a cutting from a friend that stated it was from a cacti tree forest from Puerto Rico . Found a pic of it but it’s not that great but it gives an idea of the shape and how tall it was in just 4-5 years from a single 4” cuttting . 8’tall in 28” pot with 4 stems /trunks. Roxy is a cacti fan too.
