Description:
At the posted coordiants you will find two intresting rocks that are are gray and orange. These rocks are calcite. Read the Earth Cache lesson below and make some observation yourself in order to claim a find on this cache! The big rock will be called rock one and the small rock will be called rock two.
What is Calcite?
Calcite is a common mineral (CaCO₃) found in sedimentary, metamorphic, and igneous rocks. It’s a major component of limestone, marble, and chalk. You’ve probably seen it in everyday life it’s in cement, antacid tablets, and even the chalk you used in school
How is Calcite Formed?
Calcite forms in a few different ways. In oceans and lakes, calcium rich shells and organisms like coral accumulate and compact over time, turning into limestone. It can also transform into marble under heat and pressure (metamorphism). Some calcite deposits come from hot mineral rich fluids flowing through rocks, while others are created by organisms like shells or pearls.
Calcite Formation Time
Calcite formation time varies wildly depending on the process:
- Sedimentary (e.g., limestone) Thousands to millions of years. Shells and sediments slowly compact.
- Hydrothermal veins: Can form relatively fast (years to centuries) from hot mineral-rich fluids.
- Cave formations (stalactites) ~ 1 cm every 100 years (drops of water depositing CaCO₃).
- Metamorphic (marble): Millions of years under heat/pressure.
Calcite Colours & Why it’s so Colourful!
Calcite's colours come from impurities or structural quirks.
Here’s the breakdown:
- Colorless/White: Pure calcite (no impurities)
- Orange/Red: Iron oxides (hematite) substitute for calcium.
- Blue/Green: Copper inclusions.
- Pink/Magenta: Manganese ions.
- Black/Brown: Organic matter or manganese oxides.
- Multicolor/Iceland Spar: Optical effects (twinning/banding).
Weathering of Calcite
Calcite breaks down through chemical and physical processes. Acidic rain and water dissolve it, especially in low pH environments. Wind, water, sun light and temperature changes wear it down too.
Where is Calcite Found?
You can find calcite all over the world! Major sources include the USA (Michigan, Missouri), Mexico, Brazil, Iceland, the UK, India, and China. Iceland’s famous for its sparkling "Iceland Spar" with unique optical properties. Mexico has stunning cave formations, and Brazil’s got colorful calcite deposits.
Calcite in Canada 🇨🇦
Calcite is also pretty common in Canada! Here’s the scoop eh!
It can be found in sedimentary rocks (limestone, dolomite) across provinces like Ontario, Quebec, and the Rockies (Alberta, BC).
Common colours in Canada:
White/Colourless: Most common (pure calcite).
Orange/Red: Iron-rich calcite in Ontario’s sedimentary basins.
Pink/Magenta: Manganese-bearing calcite in some Quebec deposits.
Notable Spots:
Ontario: Limestone quarries (e.g., around Ottawa, Kingston).
Quebec: Calcite veins in Appalachian regions.
Alberta/BC: Rocky Mountains (marble, limestone formations).
Logging Requirements:
To log this EarthCache, please answer the questions below. (Side note group answers are acceptable but each cacher must submit their own photo!)
1. What is your estimate the size of the two rocks?
2. What mineral composition is likely responsible for the orange in these rocks? Explain your answer.
3. What kind of weathering do you think is responsible for the loss of colour in these two rocks?
4. Make a percentage estimate of how much weathering has caused the loss of colour to these rocks?
5. Photo requirement: Take a photo of yourself at the rocks and included it in your log. Your face is not required you can give a thumbs up or hold up a signature item but you must prove that you were here with your own unique photo
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