15476 (36) Porphyritic Pigeonite Basalt
Collection:
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Fact sheet

15476 (36) Porphyritic Pigeonite Basalt

15476 is a porphyritic pigeonite mare basalt with large phenocrysts, a radiate, finer-grained groundmass and a distinct foliation or lineation. It is an average-member of the quartz-normative mare basalt suite. It is light brown with green to brown zoned prismatic pyroxene phenocrysts and a few percent vugs. The cores of large pyroxene phenocrysts are relatively unzoned, with a rather sharp boundaries when they transition to high-Ca, high-Fe margins. Some pyroxene phenocrysts appear to have grown with hollow cores, now filled with fine-crystalline matrix. The overall texture indicates a two stage cooling history. The groundmass between the phenocrysts locally has variable texture from radiate to sub-ophitic. Accessories include ilmenite, cristobalite, troilite and metallic iron.

The sample weighed 266.3 grams before analysis. It has not been dated, however, another pigeonite basalt, with strikingly similar texture (15682) has been dated at 3.4 b.y.

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

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
pyroxene
plagioclase
feldspar
Accessory minerals
ilmenite
cristobalite
troilite
metallic iron
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: