I have experimented to produce high-quality pictures of rocks in thin section. I have used 100, 400, and 800 speeds of film, along with different exposure times in order to produce the “perfect” picture for different magnifications of the objects. I found that 100-speed film along with an exposure time of about 0.5 of a second produced the best results. I am trying to show the artistic qualities as well as the geological information that can be obtained from rocks in thin section.
A thin section is a piece of rock that has been ground down to a thin slice and glued to a microscope slide. Because the rock slice is so thin, light can easily pass through it. Rocks are made up of different minerals. These minerals are crystals, which can, depending on the crystallographic orientation, alter the behavior of the light when it passes through the minerals. When viewed through polarizing filters, light interference effects may be observed that result in a display of colors. These colors, which are helpful in identifying the minerals, are particularly vivid when a compensator, like gypsum or quartz, is used.
The subjects that I am photographing are very small, less than one square centimeter, and consist of oolites, quartz sandstone, quartz mica schist, quartz crystals, which produce vivid interference colors, and fossils. During the process of fossilization the organic material is replaced with mineral crystals. Most of the replacement that is shown in my photographs comes from quartz.
Matt Milden, ’99 Cedar Rapids, IA
Majors: Art, Geology
Sponsor: Paul Garvin