For many visitors, the pink halite field trip is the highlight of the weekend.
This field trip starts new each year because the field trip area
each winter. Any pink halite
in the collecting area left behind after last year's show is dissolved in this water. The photograph
below, looking south from the main road intersection on the field trip, shows the collecting on
February 26, 2000. Clearly, both sides of North-South Road are flooded with no dry surface.
As shown in the picture below, taken May 14,2000 at the same corner
as above, the halite is just
starting to crystallize, but mostly in splash areas with still nothing in the deeper pools. As can be
seen, there has still not been enough sun and warm weather to produce the natural pink color.
Over the course of the hot, dry summer, the
evaporates from the surface of these ponds,
providing an opportunity for salt crystals to grow slowly. Under these slow crystallization
conditions, individual salt crystals can become quite large - up to 2 inches across.
Surprising as it seems, microscopic halophilic
(salt loving) bacteria live in this highly concentrated
brine and when they die, they contribute dark red coloring matter to the brine. As summer wanes,
the brine turns a darker and darker shade of red, occasionally reaching the color of a fine port or
burgundy wine. Occasionally, the salt crystals trap some of this red matter as they grow, so that
you can find salt with a wide range of colors, from pure white to pale pink to a dark cranberry
magenta. Occasionally, some of the halite develops a pale green or blue tint as well, the result of
a different bacteria, this one colored blue-green. For a complete discussion of the various halophilic
bacteria, click on Why Owens Lake Is Red . This article is from the internet magazine DesertUSA
and the link is provided with the approval of the publisher.
During especially hot days the halite may
to be replaced by the mineral burkeite, and this
will form as a pseudomorph after the halite it replaces. In many ledge deposits, nahcolite will be the
dominant mineral in the hard matrix.
The best halite crystals will be found where the crystals are
growing. This means that they
must be in brine. The largest crystals form on the underside of an overhanging ledge. In those
places exposed to the surface, small crystals continually falling from the surface cover the salt,
thereby preventing the growth of large crystals. Therefore, look for a brine pool that has overhanging
ledges (even a slight overhang will be enough to form good specimens). An example of a ledge
beneath the brine surface can be seen on the right side of the picture below. The pink halite on
the left was from this left side of this ledge.
In their quest for good ledges experienced collectors will search both open brine pools and the
pressure ridges which can be recognize by their upturned summits, like a miniature mountain
range. Another tip: use your fingers to determine whether-or-not crystals are present - if you
can't feel them, they aren't there, so digging there will be a waste of time. But be careful, many
of these crystals are very sharp and surface skin cuts can happen. If you are especially interested
in the darkest red color possible, look for the brine pool with the darkest red color in the brine.
As a summary, spend enough time looking to find good specimens some before starting to dig.
Once you have found what you think may be a
specimen, you must break off the ledge in
order to collect it. A pick can also be used to chop off specimens from a shallow ledge, as shown
below. But a heavy bar (1 inch solid steel, 6 feet long, with a 2 inch blade) is quite effective for
chopping through a tough, nahcolite ledge. These can be rented at the SLG&MS General Store
in the show building.
At least sacrificial tennis shoes are necessary, although I prefer
hip waders when I collect
for the club.
Although small plates can be easily collected
near the edges of the brine pools, if you want the
big boys, you'll have to work hard. Here, Chuck Bennett shows us his famous "big bar" technique.
The yellow and green crust is mostly massive nahcolite, and it can be very tough.
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