Storied rocks with a view; along the north-facing wall of the Earth Sciences Building you will meet six spectacular slabs, each with its own backstory shaped by pressure, heat, and a whole lot of time. From fiery granites to twisted gneisses, these stones aren’t just beautiful—they’re mini-lessons in how our planet works.
The six slabs are described below, numbered from the left. CLICK each slab image to see a large, gloriously detailed version!
1. Marble: Etowah Fleuri, Tate, Georgia, USA
This striking pink-and-white stone comes from the Appalachian Mountains near Tate, Georgia. Marble occurs when limestone gets a high-pressure, high-heat makeover deep underground. In other words, marble is metamorphosed limestone. New crystals, new patterns, new look. How fabulous!
Those swirls and ribbons? They’re the result of limestone’s minerals recrystallizing under pressure. The soft pink tones come from iron and the mineral feldspar that were present before metamorphism began. Today, this type of marble is used around the world in buildings and decorative stonework.
To learn more see the page at Stone Contact builder’s market place for some details and FAQ’s related to uses of marble in building. More about marble formation can be found on the Zstone Creations blog post, “How is Marble Formed?”.
Continue to learn about each of these beautiful and intriguing slabs of rock.
2. Gneiss; Juparana, India
Gneiss (rhymes with “nice”) is a metamorphic rock, meaning it started out as something else and transformed under intense heat and pressure deep within the Earth. That “something else” could have been granite, diorite, or even sedimentary rock.
Over time, the heat and pressure cause the original minerals to recrystallize and coarsen, new minerals to grow, and the colour-banding to develop. This forms the beautiful bands and swirls you see here. That stripy pattern is gneiss’s signature look.
Heads up: In the building stone world, Juparana is often sold as “granite”. Sometimes the name refers more to the style than the specific rock type. But if you see flowing bands like this, you’re probably looking at a gneiss in disguise.
To learn more, see for example the Stone Contact company’s description page for “Juarana India Granite”.
3. Gneiss; Dakota Mahogany, South Dakota, USA
This deep red-and-grey beauty formed around 2.6 billion years ago, give or take a few hundred million. It’s made of red feldspar, smoky grey quartz, and black biotite mica, all folded and fused together by intense heat and pressure during ancient mountain-building events.
Like most gneisses, Dakota Mahogany has those telltale light and dark bands, usually stretched or bent by tectonic forces. Rocks like this make up some of the oldest crust on Earth – the literal foundations of continents. See a brief description with a discussion of this stone supply company on the Dakota Mahogany page at the “Use Natural Stone” website (2023). Want to see something even older? Check out the Acasta Gneiss in our Main Gallery. It’s one of the oldest known rocks on the planet! See Natural Resources Canada’s page “Where do you find old iconic rock stars? In Canada, of course!” (2023) which discuss the Acasta Gneiss and the age of rocks is determined.
4. Granite; Carmen Red, Finland
This rich, deep red granite is a favorite for buildings, countertops, and monuments around the world – and it’s easy to see why. Its even texture and bold colour make it both practical and eye-catching.
But wait – is it really granite? Or could it be gneiss? Here’s how to tell:
Granite forms from slowly cooled magma deep underground. It’s an igneous rock, meaning it crystallized from a melt and hasn’t been reworked by pressure or heat since. That’s why granite tends to have a coarse, even texture without the banding or swirls you’d see in a metamorphic rock.
Gneiss, on the other hand, has been through the wringer—squeezed, heated, and folded under intense pressure. If you see flowing patterns or dramatic colour bands, you’re probably looking at a gneiss.
Take a close look at this one. No stripes? No swirls? You’ve got yourself a true granite. A succinct description of the difference between granites and gneisses is on the GeologyIn website.
5. Granite; Rosa Porino, Spain
This soft pink stone is a classic example of what most people (and the building industry) call “granite.” And they’re not wrong, but geologists like to be a bit more specific.
In geology, true granite is an igneous rock made mostly of quartz, potassium feldspar, and plagioclase. It forms when magma cools slowly deep beneath Earth’s surface giving those big, visible crystals time to grow. That’s why granites have that speckled, coarse-grained look.
Builder’s note: In construction, “granite” is often a catch-all term for any tough rock made of silicate minerals, even if it isn’t technically granite. Rosa Porino is the real deal though, geologically speaking. It looks great in the kitchen, too! Learn more from the Zstone Creations blog post, “Is Granite Intrusive or Extrusive?”.
6. Gneiss; Kinawa, Brazil
This rock may be labeled as gneiss, but it’s technically a migmatite – a rock caught between two worlds. Part metamorphic, part igneous, migmatites form when a rock like gneiss gets so hot that parts of it begin to melt, while other parts stay solid. The result? A beautiful swirl of dark and light layers that record a geological identity crisis in stone.
These hybrid rocks are most often found in ancient parts of the Earth’s crust like the Precambrian cratons of Brazil and Canada. These rocks have seen billions of years of tectonic drama, so they contain clues that geologists use to unravel that history.
Shiny secrets: To give slabs like this a polished finish, stoneworkers sometimes use a clear epoxy resin to fill tiny surface pits or cracks. It’s not always obvious, but it helps the rock shine and stand up to weather over time. See further descriptions on the corresponding page at the granite supply company International Granites.