Gretchen, Friday 20 October 2006
Each time we find a fresh meteorite, we record its position in latitude and longitude using a Global Positioning System (GPS). The biggest meteorite we’ve found is about the size of a small apple and the smallest about the size of the tip of my thumb.
We then make a preliminary guess about what kind of meteorite each one might be.
There are three main types of meteorite: Stony, Iron, and Stony-Iron. All the ones we’ve found have fallen into the Stony category. We can tell this by their weight - slightly heavier than an Earth rock of the same size - and also because theyâ€™re not very magnetic, unlike the many meteorites which contain some metal and so have some magnetism.
We’ve found two different kinds of Stony meteorite in our search. The first type, ordinary Chondrites, are quite common and come from asteroids that have been only slightly heated, and not melted.
The other type, which we found at Camel Donga, are called Eucrites (a type of Achondrite). These come from an asteroid that had melted and differentiated - like the Earth - into a core, mantle and crust. These Eucrites are thought to come from the crust of a specific asteroid - 4 Vesta. This type of meteorite is much more unusual, so we were happy to be able to find several pieces of this one.
There have also been some meteorites about which we’re not quite sure, so we’re going to have to wait until we get them in the lab to determine what kind they are.
After our preliminary assessment, we’ll put the meteorite into a bag, label the bag with a field number, the date it was found and the area.
We’ll take the meteorites to the Western Australia Museum, where Alex will give them numbers, then cut off a portion of each meteorite to send to the Natural History Museum where Caroline and I will classify them when we get back.