15362 (6) Anorthosite
Collection:
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Microscope
Click the microscope button to view a thin section for this sample.
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Fact sheet

15362 (6) Anorthosite

15362 is from a rake sample and is a cataclastic ferroan anorthosite that proved difficult to date. It consists of 98% plagioclase (An96.5), 2% orthopyroxene (Wo2En59) and trace augite, ilmenite, chromite and troilite. The plagioclase has been badly crushed and annealed. The wide spread in composition of pyroxene indicates that the parent rock was held at subsolidus temperature for a long time.

The sample weighed 4.2 grams before analysis. A lower limit for the age of 15362 is given as 3.98 b.y. (Ar/Ar), but the sample did not yield a good plateau. The simplest explanation of the Ar release pattern is that material older than 4.1 b.y. was extensively, but not completely, outgassed around 3.92 b.y.

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

The mounting resin of this thin section has deteriorated over time and now contains clusters of colourful dendrites in and around the thin section.

About this collection

The Apollo 15 landing site was in the Apennine Highlands, and close to Hadley Rille — a long, narrow winding valley. Approximately 76 kg of lunar material, including soil, rock, core-tube and deep-core samples, were returned to Earth.

This mission was the first flight of the Lunar Roving Vehicle which allowed the astronauts to venture further from the Lunar Module than in previous missions. During three periods of extravehicular activity, or EVA, on July 31st, and August 1st and 2nd, Scott and Irwin completed a record 18 hours, 37 minutes of exploration, travelling 17.5 miles, in the first car that humans had ever driven on the Moon.

Apollo 15 was launched on 26 July 1971.

Sample details

Collection: Apollo 15
Type
igneous
Rock-forming mineral
plagioclase
feldspar
Accessory minerals
pyroxene
ilmenite
chromite
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: