Designed by WZMH Architects, Scotia Plaza was completed in 1988 and remains one of the tallest skyscrapers in the city at 275 metres high.
Welcome to one of the most distinctive buildings in Toronto, and certainly the most colourful one in the financial district.
The Scotia Plaza complex is notable for its deep red hue, which comes from it's exterior cladding, Napoleon Red Granite - or as its known from its quarry site in Sweden as Vånga Red Granite. During the construction of this flag-ship commercial complex, this granite was chosen for its vibrant hues and durable structural qualities, and promptly cut and polished in Italy, imported to Canada, and used for the exterior and some of the interior surfaces.
The Task: Observe
The goal of this Earthcache is to demonstrate the compositional qualities and intrinsic values that make this stone unique compared to more commonplace types of granite and igneous rocks
The Geology Lesson
What is Vånga Red Granite?
Vånga Red Granite (commercially known as Napoleon Red Granite) is called such due to it's origins in Vånga, Sweden. Despite it's branded name, it's actually a fine-grained red orthogneiss of the Silurian period (443.1 - 419.62 Million years ago), containing the same components found in gneiss.
What is an Orthogneiss?
An orthogneiss is formed by the metamorphism of igneous rocks, and retains much of the mineral content from its igneous origins.
What Is a Gneiss?
Gneiss is a foliated meta-morphic rock, identified by its bands and lenses of varying mineral composition. Some of these bands (or lenses) contain granular minerals like quartz and feldspar that are bound together in an interlocking texture.The banding is usually due to the presence of differing proportions of minerals in the various bands; dark and light bands may alternate because of the separation of mafic (dark) and felsic (light) minerals. Banding can also be caused by differing grain sizes of the same minerals. The mineralogy of a particular gneiss is a result of the complex interaction of original rock composition, pressure and temperature of metamorphism, and the addition or loss of components.
Some specimens of gneiss contain distinctive minerals characteristic of the metamorphic environment. These minerals might include biotite, cordierite, sillimanite, kyanite, staurolite, andalusite, and garnet. Gneiss is sometimes named for these minerals, examples of which include "garnet gneiss" and "biotite gneiss."
How Does Gneiss Form?
Gneiss usually forms by regional metamorphism at convergent plate boundaries. It is a high-grade metamorphic rock in which mineral grains recrystallized under intense heat and pressure.
This alteration increased the size of the mineral grains and segregated them into bands, a transformation which made the rock and its minerals more stable in their metamorphic environment.
Gneiss can form in several different ways. The most common path begins with shale, which is a sedimentary rock. Regional metamorphism can transform shale into slate, then phyllite, then schist, and finally into gneiss. Sometimes, however, layering may form solely due to chemical processes that concentrate different minerals in different layers.
During this transformation, clay particles in shale transform into micas and increase in size. Finally, the platy micas begin to recrystallize into granular minerals. The appearance of granular minerals is what marks the transition into gneiss.
Based on the information provided above, and a satisfactory study of the stone on site at the posted coordinates, you will have more than enough information to provide answers to the questions at the bottom of the page. Please note that you should provide evidence for your answer/argument on why you chose your answer.
Questions
1) Find a large mineral deposit in the stone (lighter or darker shape) at the posted coordinates: Estimate how large this deposit is.
2. a) What are these mineral deposits composed of?
b) Do they appear to present as a pattern on the surface of the granite?
3.) Given what you've learned, why do you think this rock is medium grained, and not coarse (larger-grained)?
4.) MANDATORY Take a photo of either yourself or a signature object/your GPS/ your thumb in the front of the plaza at (Waypoint #2) (beside the polished stone of this building*)
I will also accept images taken from the inside, in the massive atrium that connects to the PATH network. Please message it to me alongside your answers, but it must be provided to prove you visited the site.
*As with any Earthcache, please message me your answers to these questions before logging.*