MIAC Introduction to meteorites

Location Map of known Canadian Meteorites

This map shows the locations of the meteorites found in Canada. Red dots indicate meteorites recovered soon after their fall was observed ('Falls'). Green dots locate specimen discovered by chance many years after they fell to earth, possibly unnoticed ('Finds'). A number of interesting features are apparent: the surprisingly low total number of meteorites for a country of the size of Canada undoubtedly reflects the sparse population and the relatively small proportion of worked land. Thus finds and falls are concentrated in more populated regions, the farmlands of the prairies, the St. Lawrence lowlands and southern Ontario. It is noteworthy that although a few meteorites have been found in the enormous areas of the Yukon and Northwest Territories, not a single fall has been recovered. Even when observations pinpoint the area of a fall in such a region very accurately, recovery from bush country is more difficult than the search for the proverbial needle in a haystack.

Classification of meteorites

The three principal categories of meteorites are stony, stony irons and irons. Stony meteorites are divided further into chondrites and achondrites, principally on the presence or absence of chrondrules (spherical bodies up to a few mm in diameter). To date over 200 different minerals have been found in meteorites and this number is increasing. Some only exist in trace amounts, however, or in rare meteorite types. With the exception of the forms of iron, the other common minerals in meteorites are also found in terrestrial rocks.

Orthopyroxene - (Mg,Fe)SiO₃
Diopside - (Mg,Fe)CaSi₂O₆
Olivine - (Mg,Fe)₂SiO₄
Serpentine - (Mg,Fe)₆Si₄O₁₀(OH)₈
Plagioclase - (Ca,Na)(Al,Si)₄O₈
Kamacite - alpha Fe,Ni 4-7% Ni
Taenite - gamma Fe,Ni 30-60% Ni