Wikimedia Commons

File:Porphyritic andesite (Sugarloaf Intrusion, Kate Peak Formation, Middle Miocene; Sugarloaf Hill, Six Mile Canyon, east of Virginia City, western Nevada, USA) (15630386757).jpg

Original file ‎(3,000 × 2,492 pixels, file size: 3.56 MB, MIME type: image/jpeg)

Captions

Captions

Add a one-line explanation of what this file represents

Summary

edit
Description

Porphyritic andesite from the Miocene of Nevada, USA (6.1 cm across at its widest).

Andesite is an intermediate, extrusive igneous rock. Extrusive rocks form at or near the surface, or on the seafloor. Andesites are "supposed" to have an aphanitic texture (finely crystalline), but most are porphyritic. Porphyritic-textured igneous rocks have a mix of large and small crystals. The large crystals are called phenocrysts. Surrounding the phenocrysts is the groundmass, consisting of small crystals. Mineralogically, andesites are dominated by plagioclase feldspar, plus amphibole and/or pyroxene.

The andesite shown above is from a shallow subsurface intrusion that represents the eroded remnants of a Miocene stratovolvano in western Nevada. The phenocrysts include whitish-gray plagioclase feldspar (andesine to bytownite), dark-colored hornblende amphibole, and dark-colored biotite mica (locally altered to chlorite).

Stratigraphy: Sugarloaf Intrusion (intrusive andesite dome), Kate Peak Formation, lower Middle Miocene, 14.53 Ma

Locality: Sugarloaf Hill, northern side of Six Mile Canyon, ~2 air miles east of Virginia City, southern Storey County, western Nevada, USA (39° 18’ 27.13” North, 119° 36’ 31.85” West)
Date
Source Porphyritic andesite (Sugarloaf Intrusion, Kate Peak Formation, Middle Miocene; Sugarloaf Hill, Six Mile Canyon, east of Virginia City, western Nevada, USA)
Author James St. John

Licensing

edit
w:en:Creative Commons
attribution
This file is licensed under the Creative Commons Attribution 2.0 Generic license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/15630386757 (archive). It was reviewed on 4 November 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0.

4 November 2019

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current14:41, 4 November 2019Thumbnail for version as of 14:41, 4 November 20193,000 × 2,492 (3.56 MB)Ainz Ooal Gown (talk | contribs)Transferred from Flickr via #flickr2commons

You cannot overwrite this file.

There are no pages that use this file.

Metadata

This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it. If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. The timestamp is only as accurate as the clock in the camera, and it may be completely wrong.

Retrieved from "https://commons.wikimedia.org/w/index.php?title=File:Porphyritic_andesite_(Sugarloaf_Intrusion,_Kate_Peak_Formation,_Middle_Miocene;_Sugarloaf_Hill,_Six_Mile_Canyon,_east_of_Virginia_City,_western_Nevada,_USA)_(15630386757).jpg&oldid=734117637"