The SAND LAB involves the identification of various BEACH, RIVER and DUNE sands through microscopic investigations.
As you look at each sand you should observe mineral or rock content, rounding of the grains, size of the grains and the sorting of the grains. These are all clues as to the environment of deposition of the sand.
Following are photographs of the sands taken through the eyepiece of the microscope:
DUNE SANDS:
IN LAB CORAL PINK SAND DUNES STATE
PARK UTAH. Note the high degree of sorting, rounding and fine
grained nature of this sample.
IN
LAB WHITE SANDS NATIONAL MONUMENT NEW
MEXICO. This unusual dune sand is composed of sand sized
crystals of gypsum. The angular nature of the grains is atypical of dune
sands but instead a growth of crystal faces on the gypsum.
ALGODONNES DUNES CALIFORNIA. This dune
(near the Colorado River) is fairly well sorted and sub rounded. It is
also fairly fine grained.
KELSO DUNES CALIFORNIA. This is a
typical dune sand in that it is very well sorted and fine grained and atypical
in that one of the dominant minerals is an iron-titanium mineral called
ilmenite
(black grains).
BEACH SANDS:
CANCUN MEXICO. This beach sand is
composed of shell fragments. In the high energy beach environment the
shells are quickly broken and eroded. The shells in this sample are even
polished by agitation in the surf zone. Notice also that this sand is only
moderately sorted.
IN
LAB OOLITE BEACH, GREAT SALT LAKE UTAH.
Oolites are concentric, sand sized concretions of mineral matter, in this case
calcium carbonate. The mineral rich waters of the Great Salt Lake have
created these oolites along the north shore of Antelope Island by agitating
grains within the surf zone. As the grains move, they are coated with
calcium carbonate - layer by layer, until they are too big to be moved by the
currents. Notice the rounding of the grains and the well sorted nature of
this sample. Oolites are normally associated with beaches.
IN LAB SANDY BEACH, ROCKY POINT
MEXICO.
Shell fragments dominate this sample. Note the variation in color and rounding of these sand sized shell fragments. Included with the organics are quartz grains (clear to white or milky). The shell fragments are derived from invertebrates living just offshore. After these poor little creatures pass on to the big tide pool in the sky... their shells are carried shoreward by currents to be beaten into sand by the breaking waves. Eventually these grains will be obliterated completely but there are others to replace them.
NAPOOPOO BEACH, HAWAII.
This beach sand shows the influence of the lava flows that make up the Hawaiian Islands. The beach sand is dominated by olivine grains and basalt fragments. The abundance of shell fragments clearly indicates its beach environment.
IN LAB CHOLLA BAY, ROCKY POINT MEXICO
Shell fragments are an important part of this sample. Cholla Bay is a "low energy" environment where the shell are able to survive for longer periods of time than in the "high energy" environment of Sandy Beach. More delicate fragments can be seen in the sand sample and occasionally micro fauna can be identified as well. This is a poorly sorted beach sand primarily because of the abundance of shell fragments. There is also an abundance of quartz in the sample. The source of the quartz is a nearby granite intrusion called Pelican Point.
RIVER (FLUVIAL) SANDS
TOPAZ WASH, TOPAZ MOUNTAIN UTAH
This poorly sorted and angular sand is dominated by rhyolite sand grains. The clear grains are topaz - not quartz. The topaz has a well developed cleavage that distinguishes it from quartz.
SAN PEDRO RIVER, ARIZONA
This is a classic example of a river (or fluvial) sand. It is very poorly sorted and angular. Quartz is the dominant mineral in the sample but there are grains of feldspar present.
IN LAB GILA RIVER, ARIZONA
This sand is very much like the San Pedro River in that is is very poorly sorted, angular and dominated by quartz grains.
IN LAB RED MOUNTAIN, ARIZONA
Red Mountain is a basaltic volcanic mountain in northern Arizona. The sand is from an ephemeral stream along its eastern flank. The sand is poorly sorted and angular. Olivine and basalt fragments dominated the sediment with an occasional clear feldspar grain.
IN LAB RUBY RESERVOIR, MONTANA
Sorry, no rubies, just garnets. This sediment was taken from a small stream that empties into Ruby Reservoir. It is very angular and poorly sorted. The colorful, gemmy grains represent various hues of garnets.
IN LAB LYNX CREEK,
ARIZONA
The area where this fine grained sand was taken is a popular spot for gold panning. It has been set aside by the National Forest Service for that purpose - "recreational panning". It is located among many placer claims in the area around Prescott. True to its fluvial depositional environment, it is poorly sorted and angular.
UNKNOWNS:
#1 BEACH (NAPOOPOO BEACH -SEE ABOVE)
Key to identification is the abundance of shell fragments.
#2 BEACH (FIRE ISLAND, LONG ISLAND, NEW YORK)
Key to identification is the medium sorting, somewhat rounded and the presence of a few shell fragments.
#3 DUNE (KELSO DUNES CALIFORNIA)
Key to identification is the fine grained nature of the sand and the high degree of sorting.
#4 RIVER (FORD CANYON, CALIFORNIA)
Key to identification is the very angular nature of the sand, presence of feldspar and the fact that it is very poorly sorted.
OTHER INTERESTING SANDS:
SOUTH POINT HAWAII
BLACK SAND BEACH, HAWAII