This is a file from the Wikimedia Commons. The description on its description page there is shown below.
Commons is attempting to create a freely licensed media file repository. You can help.
Pollucite (Caesium mineral)
Source: http://resourcescommittee.house.gov/subcommittees/emr/usgsweb/photogallery/ ; English Wikipedia, original upload 3 August 2004 by Chris 73
This image is a work of the "Minerals in Your World" project, a cooperative effort between the United States Geological Survey and the Mineral Information Institute. The images were featured in the "Minerals and Materials Photo Gallery" on the website of the U.S House Subcommittee on Energy and Natural Resources. As a work of the U.S. federal government, the image is in the public domain.
The following pages on the English Wikipedia link to this file (pages on other projects are not listed):