Meteorites

4. Meteorites
Most of the meteorite discoveries in Finland have been stony meteorites, as well as one iron meteorite.

  1. Stony meteorites:
    a) Chondrites contain silicate grains, aka chondrules, often olivine and pyroxene as well as usually 15–30% of iron. This is the most common type of meteorite.
    b) Achondrites do not contain chondrules (metamorphosis).
  2. 2 The foremost stony-iron meteorite is the pallasite, which has olivine crystals (peridot gemstone!)
  3. Iron meteorites always contain 5–25% of nickel, as well as rare metals that help to identify them, such as germanium, gallium and iridium. They are strongly magnetic. The surface of iron meteorites is bumpy, burnt black or rusty. A total of around 5,000 meteorites have been identified. Around 500 meteorites weighing over 0.5 kilograms fall to Earth every year, two thirds of which fall into the sea. Only 5–6 of them are discovered annually. The best location for meteorite discoveries is the Antarctic.

5. Meteorite Impact
The massive impact explosion released gas and spread it around with the force of a violent tempest. The wind speed close to the impact location has been calculated at up to 1,000 metres per second. The blast wave bringing down trees, the tidal waves as well as the rain of hot rocks were deadly near the impact location and even hundreds of kilometres away. The meteorite impact caused earthquakes and massive landslides, and the hot meteorite fragments resulted in wildfires. The dust and chemicals rising to the air from the impact blocked out sunlight for several years. In the oceans, the photosynthesising phytoplankton died from the lack of light, killing off countless plankton-eating molluscs and consequently, mollusc-eating marine vertebrates. Some deep-sea organisms, shallow-water amphibians and some omnivores as well as decomposers survived. Terrestrial plants perished in extensive areas, resulting in the death of those herbivores that had survived the earlier devastation of the impact. Carnivorous dinosaurs eating the herbivores died accordingly.