have
been deposited either at the same time from lime-saturated water of the
pools or..later by solutions penetrating somewhat porous rock. Later
action, possibly by hot springs, has apparently leached portions of the
tuffaceous rock to porous vesicular masses.
The
sedimentary rocks contain a bed of vesicular basalt near their top, and
in this basalt the bloodstone occurs. The strata have been tilted and
broken by block faulting and contacts are covered with talus slopes in
many places, so that it is difficult to trace any horizon far.
The
jasper and bloodstone occur in irregular nodular and kidney-shaped
masses unevenly distributed through altered phases of the vesicular
basalt. The nodules range from about an inch across up to nearly 1 foot
in thickness, and most of them are surrounded by shells of dark-green
impure opal or soft yellowish-green, rather porous material, which is
probably a clayey aggregate. In the largest pit some of the nodular
masses occur irregularly distributed in a warped layer having a
northwest strike and a northeast dip. The various openings in which
bloodstone and jasper have been found, however, do not indicate any
definite occurrence in veins or belts of separate deposits.
Red,
yellow, and green jasper are the most common, but in places the red and
the green are so blended as to yield bloodstone. The bloodstone shows
hard, dense, dark-green plasma or jasper with blood-red spots, patches,
and streaks. The heliotrope variety of bloodstone, in which the red
occurs in small round spots in the green, is rare in the Myrick
prospects, but a quantity of bloodstone showing irregular patches and
streaks of red in green is found. Jasper of various shades of red,
brown, and yellow occurs in nodules several inches across, with or
without the green. In some specimens yellow or brownish spots and
streaks are scattered through the green, similar to the red in the
bloodstone. Some of the larger lumps of jasper show mottlings in
Tarious shades of red with or without brown and yellow. Some of the
patches of color in the bloodstone are formed by a crushing of the
larger pieces and later a cementing by chalcedony or jasper fillings.
Such bloodstone shows an abundance of small faults with straight
con-between the red and the green. Occasional seams and veinlets of
gray chalcedony cut the jasper and bloodstone, filling fracture lines
and joints.
The
jasper and bloodstone from this locality take a high polish, and the
cut gems show a wide range of patterns and color variations. Stones may
be cut showing dark, bright, or dull red, brown, yellow, or green, or
pleasing combinations of these colors. The gems are suitable for
various forms of jewelry, especially for persons not desiring flashy
gems. In cutting, the lapidary should exclude all of the dark-green
opal shell surrounding the jasper and bloodstone, for this is brittle
and will crack after cutting.
Numerous
specimens of jasper with more or less associated chalcedony have been
received from Mr. Joseph Ward, of Barstow, Cal. Mr. Ward has collected
these from several claims which he has located b the Death Valley
region of San Bernardino County, and some of the specimens may have
come from Nevada. The jasper shows a wide range of color and markings
and would furnish very attractive gems. Some of the jasper shows
mosslike patterns of red, brown, er yellow, with patches of gray or
blue chalcedony. In other speci-
60326°—m r 1913—vol 2-------i3
