MINERAL PRODUCTS.
39
In Arkansas flint pebbles have been noted at many places in
Greene, Craighead, Poinsett, Cross, and St. Francis counties, along
Crowleys Bulge, which is paralleled by the St. Louis, Iron Mountain
& Southern Kailway. From 4 to T miles west of Paragould, in
Greene County, where a public road crosses the highest part of the
ridge, beds of gravel not exceeding 5 feet in thickness occur, usually
overlain by 1 to 5 feet of loam. The gravels consist chiefly of gray,
brown, and pink angular or fairly well-rounded pebbles of flint and
chert, the largest 6 inches in length, and a considerable percentage of
white, partly rounded to smoothly rounded pebbles of quartz, the
largest 1 inch in length. An exposure on the property of Mrs.
Mahala Shelton, 6 miles southwest of Jonesboro, in Craighead
County, on the south side of one of the small headwater streams of
L’Anguille Biver, shows from 4 to 11 feet of gravel, consisting
mainly of angular to party water-worn brown chert pebbles and
cobbles, reaching a maximum dimension of 1 foot. Bed, pink, gray,
and black chert pebbles and a few smoothly rounded pebbles of pink
and white quartz were also observed. Excavation for road material
1 mile east of Wynne, in Cross County, just south of the St. Louis,
Iron Mountain & Southern Kailway, showed 16 feet of gravel, con
sisting chiefly of angular to fairly well rounded pebbles and cobbles
of brown and gray flint and chert as much as 6 inches in length, with
some well-rounded quartz pebbles, lying in a matrix of coarse red
dish sand. This material is covered by about 10 feet of loam.
In northeastern Mississippi gravels carrying abundant flint peb
bles have been noted in Tishomingo County, a locality about 2% to
3 miles east of Iuka being especially mentioned. Some of these de
posits are 50 to T5 feet thick and cover large areas. The flints are
only in part well rounded and portions of the deposit are iron
stained. The gravel is extensively excavated for use in road making.
In Texas light opalescent to black flint pebbles are abundant at
several localities. They are well exposed along the river bluffs near
Austin, Travis County, where they have weathered out of the lime
stone. They also occur along Nueces Biver near Oakville, in Live
Oak County, and over large areas near Tilden, in McMullen County.
Only here and there are these flints well rounded, and many of them
are coated with a thin film of iron oxide.
For certain kinds of tube mill grinding—as, for example, the
grinding of feldspar or of crystalline quartz for making pottery—
pebbles practically free from any iron-bearing mineral must be
used, for even small specks of iron-bearing minerals produce stains
in pottery on firing. For other purposes, however, as, for example,
the grinding of gold ores preparatory to cyanidation, the same free
dom from iron is not necessary, and rounded pebbles of various kinds
of hard rocks collected from benches, stream beds, or gravel deposits