A rock featuring a white calcite vein in a rare ‘petal’ formation has been extracted from the construction site of the future McGill Sustainability Park.
Attached to a chunk of grey stone, the full rock is the approximate size of a microwave. It was discovered by construction workers north of Pine Avenue.
“The team was excited when they found it,” said Cynthia Lee, Senior Advisor, Strategy and Operations for the McGill Sustainability Park project. “The specimen looks strikingly different from the rest of the dark grey rock that has been extracted so far; it was quite a dramatic moment.”
Morgann Perrot, Faculty Lecturer in the Department of Earth and Planetary Sciences, and Claire Musajo, a PhD candidate in stratigraphy, took samples from the discovery site to learn more about its surroundings.
They hypothesize that the calcite structure was created approximately 120 million years ago following the formation of Mount Royal. The surrounding rocks date from approximately 450 million years ago.
While calcite is a common mineral, well-formed petal shapes are rare. “You don’t see this often in the field – this is only my second time,” said Perrot.
“These are well-formed single crystals with sharp distinct faces. Calcite is often white veneer in a crystal shape, but they’re rarely visible to the naked eye because the crystals don’t have enough time to develop. In this case, the crystals had just enough time and space to develop recognizable faces. Impurities or changing conditions distorted their final form, creating their petal-like appearance.”
The results are notable. “This is the kind of stuff you see in a museum,” confirmed Musajo.
There are already plans to display the rock formation in the future – most likely inside the Sustainability Park when the building is completed.