GEMS AND PRECIOUS STONES. 1031
plentifully
scattered over the fields through a distance of about 200 yards in an
east of north and west of south direction. The road from the house to
town crosses this lead. A few small test pits have been made, one
northeast and others southwest of the road.
The
country rock exposed near the amethyst prospects is hornblende gneiss
and schistose diorite inclosing granite and pegmatite. The strike of
the diorite is N. 10°-45° E. and the dip 40°-60° SE. The lead of
amethyst cuts this at a small angle having a more northerly trend. The
pit northeast of the road was made some years ago and is now filled up.
Many pale amethystine quartz crystals are scattered over the surface
here, and Mr. Donald states that amethysts were found equal in color to
those from the later pits. In a trench about 4 feet deep and in other
small pits on the southwest side of the road several seams and pockets
of amethystine quartz and amethyst crystals were found in dark-red
clay, probably decomposed horn-blendic rock. The seams were irregular
in size and direction. In places they opened into pockets of crystals.
A
large number of amethysts were plowed up in the field a few yards south
of this place, at which pomt an irregular vein striking N. 15° W. with
a vertical dip was exposed by a pit 2-1/2 feet deep. This vein
was inclosed in hornblende gneiss saprolite and ranged from 2 inches
thick at the surface to 12 inches thick in the bottom of the pit. The
thicker part was composed of more than one streak of crystals embedded
in red clay. A lump of clay about 12 inches thick removed from the vein
apparently contained 4 streaks of amethyst crystals, 1 to 3 inches
thick, with red-clay filling between. These four streaks were in
reality only two veins lined with a layer of crystals on each wall. The
crystals grew with their points turned toward the opposite wall of the
vein, but failed to fill the fissure in which they formed. In this way
veins with typical comb structure were produced with cavities or vugs
in the middle. By weathering the inclosing hornblende gneiss was
changed into a red clay saprolite and some of this clay was washed into
the cavities in the veins.
A
quantity of amethysts were plowed up in the field about 20 yards south
of this pit. The groupings of the crystals found here mdicate a deposit
similar to that exposed in the pit just described.
No
fine gem amethysts were seen at the Donald prospect, but the
examination was not made under most favorable conditions. The majority
of the crystals are rudely developed owing to mutual interference
during growth. Most of them have the rhombohedral terminations at one
end with only part or none of the prism faces. The rest of such
crystals show striated indentations formed by contact with other
crystals. Most of the amethysts from the 2-1/2-foot pit described above
are coated with a shell of lighter colored or gray quartz less than a
millimeter thick. The stones range from practically colorless, to
amethystine quartz, to crystals with a fine deep-purple color. As is
common in amethysts the color is not evenly distributed through the
crystals, but is stronger in one part than another. The patches of
color, are influenced by crystal structure as shown by their shape and
position. The majority of the crystals are not highly transparent, but
a few were seen which would cut into small clear gems of rich violet
color.
Amethyst has also been reported on the Wingo place, about 4 miles south of Charlotte Court House.
