File:Photomicrograph-porphyritic-aphanitic-felsic-rock-USGS.jpg
Jump to navigation
Jump to search
No higher resolution available.
Photomicrograph-porphyritic-aphanitic-felsic-rock-USGS.jpg (400 × 267 pixels, file size: 31 KB, MIME type: image/jpeg)
Summary
| Description |
English: Photomicrograph of a porphyritic-aphanitic felsic rock. Plagioclase phenocrysts (white) and hornblende phenocryst (dark; intergrown with plagioclase) are set in a fine matrix of plagioclase laths that show flow structure. Plain polarized light; length of photo is 2.6 mm. "Most felsic rocks are porphyritic with phenocrysts that include plagioclase (most common), biotite, hornblende, orthopyroxene (rare), and orthoclase (rare) (fig. 4)." Middle Eocene Igneous Rocks in the Valley and
Ridge of Virginia and West Virginia |
| Date | |
| Source | Figure 4, Trip 4, Geology of the National Capital Region—Field Trip Guidebook, Circular 1264, (2004) Department of the Interior, U.S. Geological Survey http://pubs.usgs.gov/circ/2004/1264/html/trip4/fig4.html |
| Author | United States Geological Survey |
Licensing
|
This image is in the public domain in the United States because it only contains materials that originally came from the United States Geological Survey, an agency of the United States Department of the Interior. For more information, see the official USGS copyright policy.
|
 |
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 03:10, 13 December 2013 | | 400 × 267 (31 KB) | wikimediacommons>Bejnar | User created page with UploadWizard |
File usage
The following page uses this file:
