78155 (40) Feldspathic Granulitic Impactite
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Fact sheet

78155 (40) Feldspathic Granulitic Impactite

78155 is a friable white cataclasite. It has been described as a holocrystalline, weakly-coherent, polymict breccia that was metamorphosed at a high temperature and has been grouped with other rocks from the early lunar crust as “feldpathic granulitic impactites”. 65% of 78155 is granoblasic matrix with another 20% crushed material. Small clasts of polygonal anorthosite have been reported. The overall mineralogical mode is ~75% plagioclase feldspar and ~25% mafic silicates (mostly pigeonite), with trace olivine, augite and opaques. Evidence for temperatures in excess of 1100°C during metamorphism are inferred from coexisting uninverted pigeonite and low-Ca augite, and from equilibrated olivine and ilmenite. Metallic iron and merrillite are also reported. Rotations 1 & 2 show the plagioclase-rich nature of the sample.

The sample weighed 401.1 grams before analysis and has been dated at 4.12±0.04 billion years (Ar/Ar).

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
Rock-forming mineral
Accessory minerals
metallic iron
Category guide  
Category Guide
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.
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.
Selecting one or more period, for example 'Jurassic'.
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.
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).
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: