Integrated Data Services, Inc.
3591 Cedar Run Road
Bonne Terre, MO 63628 - USA
Phone: 573-431-0425
or 832-472-4205
Providing geological consulting services and technical training for the petroleum industry,
specializing in sample descriptions of cores and well cuttings from carbonate reservoirs
integrating sample data with log interpretations, petrophysics, geophysics and reservoir engineering.


Grain Size Comparators


Petrographic Supplies Order Form (pdf)

Grain Size Comparator Card .. $3.00 each

Grain Size Comparator Card

This grain-size comparator was originally designed by Clif Jordan for American Stratigraphic Company (Amstrat) in Denver in 1974. It is reissued here for CarbonateRocks.com.

The top scale is in centimeters; the bottom scale is the spectrum of roundness for grains.

The center part of the comparator shows grain-sizes in the sand-size range. These sizes are listed in three ways. The first method used lower and upper case letters to refer to sand sizes. Here, vc stands for very coarse, c for coarse, m for medium, f for fine and vf for very fine; L stands for the lower limit and U for the upper limit. For example, vcU is the upper limit of very coarse sand; vfL is the lower limit of very fine sand.

The second series of measurements shows the size range in microns. For example vfL sand ranges in size from 62 to 88 microns. Note that 1000 microns equals 1 millimeter. Thus, Cu sands range is size from 710 microns up to 1000 microns (or 1 m).

The third listing is the Wentworth phi scale, a logarithmic scale used mainly in the early studies on grain-size statistics in the 1950’s and 1960’s. Note that these values reach zero at 1 mm and become negative with coarser sizes.

Grain-size comparators are available through clif@carbonaterocks.com


Petrographic Supplies Order Form (pdf)



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