If you have just read about display rocks 7, 8 and 9 (and be sure to do so before reading about this one), you will see that this block of limestone also hosts the fossilized remains of stromatolites that lived millions of years ago.

Look for how these biosedimentary structures seem to blend together laterally. What is immediately striking about this rock are the pretty pink and white calcite crystals that fill some cavities.


Photo by Claire Milloy.

Close up view of pink and white calcite crystals in an exposed cavity on display rock 10. 

Vugs are what geologists call irregular shaped rock cavities.  What a great word. Vugs found in sedimentary rocks throughout southern Ontario are known to yield several types of exciting minerals. Beautiful examples of these crystals are shared here .

One of the most common minerals found in Ontarian vugs is calcite. Calcite, a calcium carbonate (CaCO3) mineral, makes up the rest of specimen 10 too, but it looks very different in these holes than in the rest of the rock.  This is because the calcite crystals in the vugs are large enough to see with the naked eye, whereas the calcite in the limestone slab is not. Crystals that form in bedrock voids and fractures generally ‘grow’ slowly as circulating groundwater solutions, which contain varying amounts of dissolved minerals, deposit some of their load bit by bit when the conditions are right. To see additional examples of calcite crystals found in our region, take a look at the following video about a road cut near Arnprior, about 30km north of Almonte  https://www.youtube.com/watch?v=Hvq5I0SFm3s

As you scan display rock 10, take a close look at the drill hole too.


Photo by Claire Milloy.

The rock was drilled to place an explosive charge for the excavation of a building lot in Almonte. 

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