Photomicrographs of Sands & other Substrates
Carib Sea Aragamax - 40X
Aragamax is clearly an oolitic sand - defined as "consisting of small round grains usually of calcium carbonate." The particle sizes in this photo range from about 1/2mm for the largest ones, down to about 40 microns for the smallest.
Southdown Tropical Play Sand - 40X
There are some differences in lighting and exposure for this photo, otherwise Southdown is completely indistinguishable from Aragamax.
Quickrete Play Sand - 40X
Very different from the previous two. Quickrete is a silica sand, consisting mostly of quartz grains. It has been suggested that the sharp edges on these grains are problematic for soft-bodied invertebrates that normally inhabit a deep sand bed. For this reason, silica sand may tend to harbor less life than oolitic sand.
The elongated black particles are of unknown composition, but
preliminary investigation shows they may be tar - note the small amounts
that appear to "rub off" onto the adjacent quartz grains.
May 2008 Advanced Aquarist is Now Available
International Marine Aquarium Conference '08