Why this rock is probably not a meteorite:
If you've gotten this far and have been paying attention, you might
be thinking, "That's not a meteorite because there is no fusion
crust and the exterior is too rough." (Click on image for enlargement.)
|
What is it?
This is a meteorite. It was bought from a dealer
and it was purported to be a meteorite from the desert of northwest
Africa. This is a fragment of a meteorite, with the weathered, broken
surface exposed (mm ticks on ruler). The shiny coating is not a fusion
crust but desert
varnish. Under different lighting (small
| big), shiny metal grains
appear at the surface. That's the first clue that it is a meteorite.
The rock is strongly magnetic. On a sawn surface, many shiny
metal grains can be seen (different lighting: small
| big). Together these two
features suggest that the shiny grains are not some type of oxide
or sulfide mineral, but iron metal. The finely and evenly disseminated
nature of the metal (unlike no.
011) is exactly what is observed in ordinary chondrites. The large
proportion of metal is characteristic of an H chondrite, one of the
most common kinds of meteorite. In thin section (0.03 mm thick, 4.5
cm in longest dimension: small
| big), the metal looks
gray or black. The round, light colored things are chondrules. The
reddish minerals are olivine and pyroxene (see also no.
035, which is another H chondrite).
|
|
|
