Particle Size of Southdown Sand from Home Depot
Just a quick FYI for those of you interested in the Southdown Tropical Play Sand from Home Depot
I sieved 50g of sand through a descending mesh series -- the proportions retained on each mesh size are below (i.e., the >300 um size class means that the sand passed through the 500 um screen, but was retained on the 300 um screen). The majority of the sand appeared to be oolitic aragonite, but there were a large number of identifiable pieces in the largest size fraction including fossil and non-fossil gastropods, bivalves, radiolarians, foraminiferans, urchin spines and spicules of various critters (such as sponges, corals and echinoderms). There were also a number of tiny non-carbonate rock pieces in the largest size class, including what appeared to be quartz, marble, and slate. I could not find any obvious pieces of non-carbonate rock in the smaller size fractions, however.
Size breakdown of the sand
- >500 um (= 0.5 - 2.69 mm) 14% (largest particle 2.69 mm)
- >300 um (= 0.3 - 0.5 mm) 32%
- >250 um (= 0.25 - 0.3 mm) 16%
- >180 um (= 0.18 - 0.25 mm) 20%
- >125 um (= 0.125 - 0.18 mm) 13%
- >100 um (= 0.1 - 0.125 mm) 3%
- >50 um (= 0.05 - 0.1 mm) <1%
- <50 um (= 0.001 - 0.05mm) <1%
This is roughly the exact proportions that I originally suggested in the FAMA articles as "about right" for a deep sandbed (I think I said something like "10% coarse sand, ~30% "sugar-sized" and the remainder of the bed should be made up of the finer stuff down to around at least 0.05mm or so). I just thought that some of you might be interested in this bit of info...