A Geoscience Digital Image Library
A Geoscience Digital Image Library
| Title | Ferruginous argillite (mudstone), Missoula, Montana |
|---|---|
| Description | This rock might be termed a mudstone, a term used for fine grained rocks composed of subequal amounts of quartz and clay, and lacking the texture of a shale. Although no minerals can be identified in hand specimen, microscope examination confirms the presence of quartz and clays. This specimen is labelled a “ferruginous argillite” in the Ward’s Collection of Classic North American Rocks. Translated that means it is an iron-bearing rock containing clay minerals. Sedimentary geologists might consider this a metamorphic rock, but metamorphic geologists would consider it a sedimentary rock because metamorphic fabric and minerals are very poorly developed, if at all. The sample is 9 cm across. |
| Location | USA ▹ Montana. Near Missoula. |
| Photographer | Mike Davis. 2001-04-26. |
| Collection | Ward’s University Rock Collection #200. |
| Key words | ferruginous, argillite, Montana |
| Tech details | 644 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera, 60mm Nikon AF micro lens. |
| GeoDIL number | 438 |
 | |