• Question: what is your favorite rock?

    Asked by anon-198984 to Alex, Natasha on 10 Mar 2019. This question was also asked by anon-198917, anon-198925.
    • Photo: Alexander Allen

      Alexander Allen answered on 10 Mar 2019:

      Hmmm that’s quite thought provoking… I often work with crystals of some sort. So I’m going to start by narrowing my choice down to an igneous type (a rock that is produced in a volcano).

      Crystals are just great to look at and have such simple chemistry. For example a sapphire is just a sample of Aluminium Oxide. You can find these types of gem in all sorts of igneous rock such as granite…

      I also have to give a shout-out to sedimentary rock as they often contain fossils that are super interesting…

      My final answer is possibly Crocodile Rock (The Elton John song). This pun may cost me votes and I’m sorry…

    • Photo: Natasha Dowey

      Natasha Dowey answered on 13 Mar 2019: last edited 13 Mar 2019 2:14 pm

      My favourite rock is Serpentinite- it is a beautiful metamorphic rock (meaning it has been changed by heat and pressure) that looks like red and green snakeskin. Serpentinite was once solidified magma beneath ancient oceans, and is forced to the surface when tectonic plates come together at a plate boundary. You can see really great examples of it in one of my favourite places in Cornwall, the Lizard Peninsula (named “lizard” after the snakey “serpent” rocks!). I wrote an article on it a while back for the Geological Society, there are some pics in here too 🙂
      https://www.geolsoc.org.uk/GeositesKynance

Comments

  • Photo: Natasha

    Natasha commented on :

    I have to leap in on this question, apologies! 🙂 I am a geologist, so I get to look at a lot of rocks. Rock favourite conversations can cause fights amongst geologists. Friendships have been lost! 😉 I am a big fan of both igneous rocks (cooled from hot magma, either trapped inside the earth and revealed at the surface by erosion, or outside the earth as a volcano) and sedimentary rocks (rocks that form from particles that have been transported to the ground, perhaps by a river, or the wind, or by the sea). But my ALL TIME FAVOURITE rock is a complete wildcard. It is a rock of amazing colours and textures- in fact, the people who first named it thought it looked like a snake, and named it after one! Serpentinite is a beautiful rock. I come from Cornwall, and you find Serpentinite at a very special place called the Lizard (also named in a reptile-y fashion because of the snakeskin rocks you find there). Serpentinite is a rock that truly reflects dynamic processes within our planet. It records ancient oceans, that have long disappeared. Where the Earth’s tectonic plates move apart beneath an ocean, magma rises and forms new ocean ‘crust’ to fill the gap. This crust is layered; the upper layer consists of ocean sediments and lava erupted onto the ocean floor, while the lower levels are made of solidified magma. Serpentinite records the part of the Earth’s mantle just beneath the crust. We very rarely get to see mantle rocks at the Earth’s surface. The Lizard rocks of Cornwall were originally kilometres beneath the Earth’s surface, under an ocean, but were pushed up as two continental plates collided (a process known as obduction) over 300 million years ago! Sp… they are pretty special. If you want to see some lovely pictures of them, check out this article I wrote a while ago: https://www.geolsoc.org.uk/GeositesKynance