69955 (30) Cataclastic Anorthosite
Click the microscope button to view a thin section for this sample.
Click the microscope button to view a thin section for this sample.

Fact sheet

69955 (30) Cataclastic Anorthosite

69955 was chipped from the bottom of a 0.5 m boulder found perched on the lunar regolith. Hence, 69955 is a clast in a breccia. The sample is almost entirely made of plagioclase. Most of the plagioclase has been converted to maskelynite. Less shocked (still birefringent) patches of plagioclase within the maskelynite are as much as 3 mm across. Rare pyroxene grains are 0.1-0.08 mm across and have no visible exsolution lamellae (tiny crystals visible in rotation 2). Some relict intergranular texture is preserved in lithic clasts. A 1 mm thick layer of impact melt glass is visible on the left of our thin section (see rotation 1).

The sample weighed 75.9 grams before analysis and has not been dated.

Our thin section is slightly thick so between crossed polars some plagioclase crystals are yellow instead of shades of grey. Note that the yellow rim visible in reflected light is the remains of a gold coating applied to the sample prior to analysis.

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

About this collection

The Apollo 16 landing site was in the hilly region around Descartes crater in the lunar highlands. The landing spot was chosen to allow the astronauts to gather geologically older lunar material (Descartes Formation and the Cayley Formation) than the samples obtained in the first four landings, which were in or near lunar maria.

The mission lasted 11.1 days, with a stay on the lunar surface of 71 hours. The crew were on the lunar surface for 20.2 hours during which they traversed approximately 27 kilometers and collected approximately 96 kilograms of samples.

Apollo 16 was launched on 16 April 1972.

Sample details

Collection: Apollo 16
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: