73218 (26) Impact Melt Breccia
Collection:
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Fact sheet

73218 (26) Impact Melt Breccia

73218 is a coherent impact melt rock similar to 73216 and 73275 from the same location. The fine-grained matrix has needles of plagioclase feldspar that formed from a melt and confirms this is an impact melt rock. However, before it was a melt it was a breccia, because there are relict small clasts of anorthosite and anorthositic breccia. Rotation 1 shows a remarkable pyroxene clast consisting of a larger pigeonite crystal mantled by augite. Both display fine exsolution and the latter is also twinned. Rotation 2 shows two plagioclase feldspar-rich clasts. Metallic iron, ilmenite and troilite can be seen in reflected light.

The sample weighed 39.7 grams before analysis and has not been dated.

Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
 

About this collection

Apollo 17, the final manned landing mission, had two objectives: to obtain samples of ancient rocks from the lunar highlands and to look for evidence of younger volcanic activity on the valley floor.

This small Collection contains material deriving from both periods, including igneous rocks around 4.3 billion years old from the lunar highlands as well as younger volcanic samples dating from about 3.6 billion years ago.

Apollo 17 was launched on 7 December 1972.

Sample details

Collection: Apollo 17
Type
metamorphic
Rock-forming mineral
pyroxene
plagioclase
feldspar
glass
Accessory minerals
metallic iron
ilmenite
troilite
Category guide  
Category Guide
Title
Refers to any word or phrase that appears in the individual rock names. Names are generally descriptive; they allow users to search for broad terms like ‘granite’ as well as more specific names such as ‘breccia’. However, the adjacent descriptions of the specimens captures a wider range of general words and phrases and is a more powerful search tool.
Description
Refers to any word or phrase that appears anywhere in the descriptions of the specimens
Accessory minerals
Minerals that occur in very low abundance in a rock. They are usually not visible with the naked eye and contribute perhapssver, they often dominate the rare elements such as platinum group metals.
Rock-forming minerals
Minerals that make up the bulk of all rock samples and are also the ones used in rock classi?cation.
Timescale
Selecting one or more period, for example 'Jurassic'.
Theme
A term used to group together related samples that are not already gathered into a single Collection. For instance, there is a ‘SW England granites’ theme that includes such rock types as granite, hydrothermal breccia, skarn and vein samples.
Category
A general term used to label a rock sample. It is a useful way of grouping similar samples throughout a collection. Category names are often, but not exclusively, common rock names (e.g. granite, basalt, dolerite, gabbro, greisen, skarn, gneiss, amphibolite, limestone, sandstone).
Owner
The owner of the sample that appears in the collection. For example, NASA owns all the samples that appear in the Moon Rocks collection
We would like to thank the following for the use of this sample: