File:Quartz monzonite (Butte Quartz Monzonite, Late Cretaceous, 68-78 Ma; Interstate 90 outcrop, southeast of Butte, Montana, USA) (16168713613).jpg

Original file(1,086 × 687 pixels, file size: 1.09 MB, MIME type: image/jpeg)

Captions

Captions

Add a one-line explanation of what this file represents

Summary

edit
Description

Quartz monzonite from the Cretaceous of Montana, USA. (6.7 cm across at its widest)

Igneous rocks form by the cooling & crystallization of hot, molten rock (magma & lava). If this happens at or near the land surface, or on the seafloor, they are extrusive igneous rocks. If this happens deep underground, they are intrusive igneous rocks. Most igneous rocks have a crystalline texture, but some are clastic, vesicular, frothy, or glassy.

Quartz monzonites have the same general characteristics and compositions as true granites (= coarsely crystalline/phaneritic-textured, intrusive igneous rocks composed of quartz, K-feldspar, plagioclase feldspar, and usually one or more mafic minerals). Quartz monzonites, in contrast, have less quartz than true granites. The quartz component of quartz monzonites is 5% to 20%, whereas true granites have 20% to 60% quartz.

The Cretaceous-aged quartz monzonite shown above is dominated by orthoclase feldspar, plagioclase feldspar, quartz, and biotite mica.

Geologic unit & age: Butte Quartz Monzonite, Boulder Batholith, Campanian Stage to Maastrichtian Stage, late Late Cretaceous, 68-78 Ma

Locality: outcrop along the southern side of I-90, just east of Homestake, southeast of Butte, southwestern Jefferson County, southwestern Montana, USA (~45° 54’ 53” North, ~112° 22’ 34” West)
Date
Source Quartz monzonite (Butte Quartz Monzonite, Late Cretaceous, 68-78 Ma; Interstate 90 outcrop, southeast of Butte, Montana, 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@N05/16168713613 (archive). It was reviewed on 1 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0.

1 December 2019

File history

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

Date/TimeThumbnailDimensionsUserComment
current09:07, 1 December 2019Thumbnail for version as of 09:07, 1 December 20191,086 × 687 (1.09 MB)Ser Amantio di Nicolao (talk | contribs)Transferred from Flickr via #flickr2commons

The following page uses this file:

Metadata