Collection
Classification: IAB-sLL (IAB Iron)
An iron meteorite belonging to the low-Au, low-Ni subgroup (sLL) of the IAB complex
Observed fall: No
Year found: 1776
City, Country: Toluca, Mexico
Mass: 3000 kg
In collection
Weight (Pair) : 330 g
Certificate of authenticity: Yes
The Toluca meteorite is a well-known iron meteorite classified within the IAB complex of iron meteorites. Discovered near Toluca, Mexico, in 1776, it consists primarily of a nickel-iron alloy and exhibits prominent Widmanstätten patterns when etched and polished. These patterns are indicative of slow cooling rates within the core of its parent asteroid, allowing large metal crystals to form. The Toluca meteorite also contains silicate inclusions and trace minerals, providing valuable insights into the processes of planetary formation and differentiation in the early solar system. Its study has significantly contributed to the fields of meteoritics and planetary science.
When examining a IAB meteorite under a light microscope, several distinctive features can be observed
Widmanstätten Patterns:
Description: The Toluca meteorite exhibits prominent Widmanstätten patterns, which are intricate intergrowths of two iron-nickel alloys: kamacite (low-nickel iron) and taenite (high-nickel iron).
Observation: Under reflected light, these patterns appear as a distinctive crisscross or octahedral lattice of bands.
The kamacite bands are wider and have a matte appearance, while the taenite lamellae are thinner and more reflective.
Significance: These patterns form due to the slow cooling of the meteorite’s parent body, allowing the iron-nickel alloys to separate into distinct phases over millions of years.
