Page 242 - miningincalif1927

210 ' REPORT OF STATE MINERALOGIST.

ONYX MARBLE.

Deposits of travertine and aragonite, also referred to as onyx marble

or 'Suisnn' marble, occur in the vicinity of Tolenas Springs, six miles
north of Fairfield. Some of the material shows a beautiful banded
and wavy structure. Similar 'marble' comprises the principal lime-
stone deposit at Cement owned by the Pacific Portland Cement Com-
pany, originally utilized in the manufacture of cement. The travertine
at Tolenas Spring deposit has been quarried from time to time and
used in the making of terrazzo and for other ornamental purposes. The
deposit was last leased to S. Miletin, 121 Fourteenth Street, San Fran-
cisco. No material has been taken out since the latter part of 1926. A
tractor used in hauling from the spring to the highway has been
removed and the road to the deposit is now in poor shape.

Bibl: State Mineralogist's Report I, p. 17; IV, p. 73; V, p. 67;

VI. pp. 22, 91; VIII, p. 631; X, pp. 668-670; XII, p. 403;
XIII, pp. 632, 641 XIV, p. 311. State Mining Bureau Bull. 37,
;
p. 112; Bull. 38, p. 114. Geol. Sur. of Cal, Geol. Vol. I, p. 104.
U. S. Geol. Survey Water Sup. Pap. 338, p. 162.

PETROLEUM.

Two small areas in Solano County have been classified by Vander
Leek 1 as 'possible' oil bearing areas; 'possible' being defined as land
on which there is the slightest indication of petroleum but which
remains unproven to date (1921). The indications and localities are

described as follows: (a) "About one mile southeast of Cannon in
Sees. 11 and 14, T. 5 N., R. 1 \V., there are several well-defined 'gas
blows.' These gas blows occur along the axis of a fold in the Chico
sandstone, and in the vicinity of the 'blow' the rocks have been
burnt to a brick-red slag, (b) In the Potrero Hills, east of Fairfield,
there are numerous seepages of gas reported in the Meganos shales.'
The structural conditions in these two areas are regarded by Yander
Leek as favorable for the accumulation of petroleum.

He further states "the unfavorable factor is the character of the
formation present (contaceous) which is distinctly unfavorable for the
formation of petroleum in an appreciable amount. * Summing
these factors up, it would appear that wells drilled along the axis of
the anticlines and faults should obtain showing of oil and,
possibly, under the most favorable conditions, obtain small quantities

of oil. Whether these small quantities of oil that might be obtained
would be of commercial value can only be determined by drilling. Due
to the favorable structure and the large area of possible accumulation,
the anticline southeast of Vacaville and the dome in the Potrero Hills
may be considered as the most favorable locality to test out the
'
district.
Subsequent to the publication of Bulletin No. 89 the two areas
mentioned were drilled by the Honolulu Consolidated Oil Company
without obtaining commercial production. These wells were in the

1
Vander Leek, Lawrence, Petroleum Resources of California, with special refer-
ence to unproved areas. State Mining Bureau Bulletin 89, 1921.