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Achondrite or a chondrite EarthCache

Hidden : 10/3/2016
Difficulty:
2 out of 5
Terrain:
1 out of 5

Size: Size:   other (other)

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Geocache Description:

This Earthcache will take you to the Meteorite Museum in Northrop Hall, room 106 at the University of New Mexico Campus. The museum does not currently have regular hours of operation, but they do allow for group tours that are coordinated in advance by emailing Beth Ha at iom@unm.edu. I encourage the geocaching community to coordinate with each other to get access to the museum so that there are not too many single requests for tours. This meteorite museum is a little-known gem in Albuquerque!

Although access to the museum is free, parking close to the museum requires either a parking permit or metered parking, and the campus police are fairly quick to ticket unlawfully parked cars. The museum is available by appointment only and the museum follows the same holiday schedule as the University. If there are any questions about museum availability, please email me through my user profile, and I will respond as soon as I can. Otherwise, please email Beth Ha at iom@unm.edu to set up a visit. The museum will eventually move back to a model of having regular hours for the public, and I will make further updates on this page as that happens.

Meteorites are chunks of rock that formed within our Solar System that have fallen to the Earth. Meteorites provide the best record we have for understanding planet formation, and they provide a basis for understanding the chemical compositions of the celestial bodies in our Solar System, including the Earth. The most primitive materials in our solar system are called chondrites, and this group of meteorites has not undergone previous melting. Chondrites are complex mixtures composed of silicates, oxides, and metal. Chondrites are reported to be the primary building blocks from which the terrestrial planets were made. During the process of planet formation, many chondrite materials came together to form large planetary embryos that later combined with other planetary embryos to form the terrestrial planets we have in the inner Solar System today. This building process, aided by radiogenic heating, caused the chondritic material to melt. The metallic portion of the chondrites sank towards the center of gravity due to its higher density, and the silicate portion formed a shell around the metallic portion. This structure of a metallic core surrounded by a silicate mantle is common among all of the inner planets and many of the large asteroids in the asteroid belt (i.e., 4Vesta and Ceres). The process of separation of the metal and silicate portions of a planetary body is known as planetary differentiation. Meteorites that come from either the metallic core or the silicate mantle of a planetary body are called achondrites, and these materials have all experienced some degree of planetary differentiation.

This Earthcache will serve to walk you through the stages of planetary differentiation based on the exhibits on display in the museum. To claim credit for this Earthcache, please answer the following multi-part questions:

1. Find the display with Portales Valley H6 Ordinary chondrite. Describe how the metal is distributed in the meteorite compared to the Chico L6 Ordinary chondrite in the same display case. Name at least one other chondrite on display.

2. Find the display case with Glorieta Mtn. What kind of meteorite is Glorieta Mtn? Do you think the Glorieta Mtn meteorite is representative of the core portion or the silicate portion of a planetary body and why?

3. Find the display with the meteorite Zagami. Where does the Zagami meteorite come from? Do you think Zagami is representative of the core portion or the silicate portion of a planetary body and why? Name at least one additional meteorite on display that comes from the same parent body as Zagami.

4. Go to the meteorite case labelled pallasites. Do you think these meteorites are chondrites or achondrites and why? Name one pallasite on display, and also tell me where it was found.

Please send your responses to me via email or message from my profile. Please feel free to log before you hear back from me, but any logs that do not have an accompanying email within a month of the log will be deleted.

*****The museum is reopening, but we are still in the midst of the COVID-19 pandemic, and this cache is indoors, so please exercise caution. The University of New Mexico has asked that individuals accessing campus facilities be vaccinated. Furthermore, the hours of operation for the museum are by appointment only, so please email Beth Ha (iom@unm.edu) to schedule your visit.*****

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