DOI: 10.5066/p1summmi
title: Thin section images of hand samples and drill core from mafic to ultramafic rocks (ver 2.0, August 2025)

description: These datasets include photographic images of thin sections created from hand samples and drill core collected from mafic to ultramafic rocks from different locations across the U.S., shapefiles representing the locations of the hand samples and/or drill core collars, and images showing examples of the approximate scale on the thin section images. The samples were collected in order to help define platinum group element (PGE), copper, nickel, gold, or titanium vanadium iron resources associated with the rocks.
The images of the entire thin section, in plane-polarized (PPL) and cross-polarized light (XPL), were taken using a high-resolution digital camera on a macro stand. The PPL and XPL images were exported from the camera in both raw .CR2 and compressed .jpg format. Reflected light (RL) images of the thin sections were taking using a Keyence VHX-7000 digital microscope. The RL images were exported from the Keyence as .tif images. Thin sections with a coverslip were not imaged in reflected light.
The data is organized into zip folders containing the thin section images for each area, and zip folders containing the shapefile of the locations of the hand samples and/or drill core collars for each area. Some of the image files are split into multiple zip files due to file size upload restrictions. These zip files will have “_part(x)” as the file suffix. The zip files containing the images contain two folders, one containing the original 'RAW' unprocessed .CR2 images and associated .xmp metadata files, and unprocessed .tif images, and another folder containing processed .jpg images. The processed images were run through a series of tools in Photoshop in order to improve the appearance of the images. The images taken in reflected light were not run through the Photoshop processing.
The file name of each photograph correlates to either the drill hole and depth of the sample, or the hand sample ID from which the thin section was sourced, and whether the photograph represents a plane-polarized (PPL), cross-polarized (XPL), or reflected (RL) light image. For example, the "CLO-11_71.5_XPL.JPG" file is a cross-polarized image of the thin section sourced from a sample taken from the "CLO-11" drill hole at a depth of 71.5 feet.
The RL images include a scale bar. The PPL and XPL images do not show a scale bar, however the thin section holder, viewable in the images, can be used as an approximate scale bar. The width of the rectangular opening of the thin section holder is approximately 48 millimeters wide. See the "Scale_bar_example_PPL.JPG" and "Scale_bar_example_XPL.JPG" image files for examples.
The image files have Section 508 compliant metadata as per USGS section 508 compliancy officer guidelines. The .xmp files are included with the 'RAW' .CR2 files because the original .CR2 metadata cannot be altered. In order to add descriptive information to the metadata, the .xmp files must be included. The image metadata for the .jpg and .tif files can be viewed using software such as Adobe Photoshop, Adobe Bridge, or Windows file explorer. The raw .CR2 images edited metadata (.xmp files) can be viewed in Adobe Photoshop and Adobe Bridge, but is not viewable using Windows file explorer. For the .CR2 images, only the original metadata, created when the photograph was taken, can be viewed using Windows file explorer.