The sunny south side; four of these warm slabs are sedimentary rocks. These are generally “softer” (although not exactly fuzzy!) than the igneous or metamorphic rocks found on the other two walls. However they are all used extensively for building and decorative purposes, especially in regions where they are readily available.
The six slabs are described below, numbered from the left. CLICK each slab image to see a large, gloriously detailed version!
16. Gneiss; Kashmir Gold, India
This is a hot one – high temperatures of ~800-1000 ⁰C and moderate pressures are needed to form this attractive gneiss. Being distinctive enough to have a special name – a granulite – this type of gneiss tends to be finer-grained than other gneisses. It also has less distinct banding, and frequently includes garnet crystals.
Think: Look closely – can you spot the red garnet crystals in out specimen?
Kashmir Gold and the related “Kashmir White” granulites, are mined near Madurai, Tamil Nadu state, in India. This is nowhere near the actual Kashmir region of India; the name is simply a trade name.
17. Sandstone; Rainbow sandstone, from near Khatu in Rajasthan, India
Can you imagine a beach looking like this? Look closely to see individual sand grains that were naturally cemented together to form this rock. Regular stripes indicate variations in types of sand being deposited over time. In contrast, those irregular reddish stripes formed after deposition from water with dissolved iron moving through the rock while it was forming.
How might you use a slab like this? Sandstones are used most commonly for flooring, tiles or building stones rather than counter tops or monuments.
Think: Why do you suppose that is?
Unfortunately, the quality of stone from this quarry has apparently been declining since roughly 2018. Even rocks are not a “renewable resource”!
18. Travertine; Roman Classic Travertine, Italy (Rome)
This elegant material forms when water from hot or cold springs precipitates layers of carbonate minerals such as calcite. The patterns can be intricate and beautiful – our example here is relatively plain compared to some of the examples here.
What does its name suggest about is popularity throughout history? It has been attractive because it is hard yet relatively easy to work, it has no natural planes of weakness, it is relatively light weight, and it is found near centres of ancient civilizations. However, like all limestones, travertine may decay over time due to acid rain or urban air pollution.
Learn more: Italian travertine quarries and quarrying are nicely illustrated here.
19. Granite (quartz monzonite); Bianco Sardo, Italy (Sardinia)
Not all coarse-grained igneous rocks are true granites! This rock contains Plagioclase, quartz, Biotite and Alkali feldspar, but with less quartz and more feldspars than “true” granites. Rocks like this are also common in the Coast Mountains near Vancouver.
This hard-wearing material is perhaps one of best-known and most widely used Italian granites, popular for counters, flooring, monuments and more.
20. Travertine; Travertine Nocé, Italy
This one has a bonus feature!
Think: Look closely – try to find the embedded fossilized snails. This variety is also mined near Rome, but compared to our other specimen, it is a bit more “figured” or “patterned” and is light brown with beige inlays. It is also denser with fewer cavities, so it is more durable and less likely to deteriorate due to acid rain or pollution.
Which of our two travertine specimens would you prefer to have in your home?
21. Dolostone; Israel
Dolostone and limestone are similar but not the same! This rock is mostly dolomite – a calcium-magnesium carbonate mineral, while limestone is mostly calcium carbonate. Fossils within sedimentary rocks like dolostone, limestone or travertine may be used to determine the environment where they were deposited. They may also help determine the age of the rock.
Think: Look closely to see all the little holes in this rock. It has a relatively high “porosity” compared to many other rocks. In Israel, dolostone aquifers (underground sources water) contain a significant proportion of the country’s water supply.
To learn more about building stones used around Vancouver, check out the free online guide called Downtown Vancouver Geotour, published as a collaboration between the MineralsEd and the Geological Survey of Canada. This 26-page PDF document contains details about many stones used as building materials in Vancouver. Use it for a fascinating self-guided tour of the downtown area!