California Division of Mines and Geology 



Bull. i97 



Figure 1. Index map of Coast Ranges limestone and dolomite province. 



Deposit Descriptions 



An attempt was made to describe all of the deposits 

 in a systematic manner; and, where possible, data are 

 provided on location, ownership, history, geology, de- 

 velopment, production, estimated reserves, and perti- 

 nent references — generally in that order. 



Almost all of the large deposits and many of the 

 small ones in the Coast Ranges province were exam- 

 ined by this writer or Oliver E. Bowen (geologist, 

 Division of Mines and Geology, from 1947 to 1968; 

 now a consulting geologist). This investigator's prop- 

 erty visits were conducted mainly between April 1962 

 and February 1964, whereas Bowen's visits extend 

 over a much longer period (mainly before 1962). 

 Limestone, dolomite, and shell deposits not examined 

 include numerous minor ones plus some that have 

 been adequately described in the literature and a few 

 that could not be reached or located. Virtually all 

 deposits cited previously in the literature, regardless 

 of their economic significance, are considered in this 

 report. 



Samples and Chemical Analyses 



Most chemical analyses presented herein are of 

 hand or grab samples believed by the sampler to be 

 representative of the compositional variations at a 

 given carbonate deposit. The representativeness of a 

 given sample or set of samples, however, depends on 

 the acuity of the sampler, the accessibility and extent 

 of deposit outcrops, and the degree of weathering. In 

 some cases, processed or partly processed carbonate 

 materials (shells and other materials) were sampled 

 from stockpiles and waste piles, sometimes to check 

 beneficiated and waste materials or simply because 

 some deposits were inaccessible. For a variety of rea- 

 sons, many deposits were not sampled at all. 



Analyses of samples by commercial laboratories 

 were made prior to 1960. Most, if not all, of these 

 analyses were by wet chemical methods. Most analy- 

 ses since 1960 were made bv Division of Mines and 

 Geology laboratory staff. Until mid- 1963, these were 

 done mainly under the supervision of Charles W. 

 Chesterman, using rapid analytical techniques. In 

 1963, analytical techniques were changed to a com- 

 bined wet chemical and x-ray fluorescent method un- 

 der the supervision of Matti Tavela. Analyses made by 

 various companies and individuals are believed to 

 have been done by wet chemical methods. 



Because of the above variables — particularly the in- 

 herent sampling problems — the chemical analyses 

 presented herein should be viewed only as a general 

 guide to the composition of the deposits sampled. 



Reserves 



All reserve figures for deposits described herein are 

 estimates based on limited data — generally not includ- 

 ing drill data. These estimates are of carbonate materi- 

 als believed to be recoverable under present (1972) 

 economic and mining conditions. The type of carbon- 

 ate material (limestone, limestone and chert, dolo- 

 mite, shells) comprising each deposit is indicated 

 where reserve figures are estimated. Where little or no 

 subsurface data are available or where deposits are 

 poorly exposed, estimated reserves are presented in 

 tons per foot of depth, and no attempt is made to 

 estimate economically recoverable material. 



Definitions 



Carbonate rock, as used herein, is a general term 

 that includes all limestone, dolomite, shell, travertine, 

 calcareous tufa, onyx, caliche, marl and unspecified 

 mixtures of these. Definitions of the more specific 

 terms used in this report are: 



• limestone: A sedimentary rock composed mostly of detrital or 

 chemically deposited calcite (calcium carbonate). Metamorphosed 

 limestone (marble) is recrystallized calcite and is referred to as 

 crystalline limestone. Bioclastic limestone is a limestone composed 

 largely of firmly cemented fragmental fossil debris. 



• dolomite: A sedimentary rock, often diogenetically altered, 

 composed mainly of the mineral dolomite (double carbonate of 

 colcium and magnesium). A metamorphosed dolomite (marble or 

 dolomite marble) is referred to as crystalline dolomite. 



• shell deposits: Unconsolidated to weakly consolidated accumu- 

 lations of shells and shell debris; pure to very impure calcium carbon- 

 ate. 



• travertine: Fine to sometimes coarse crystalline, dense to vuggy, 

 banded rock composed of calcium carbonate; formed from surface 

 water at or near the earth's surface, generally near springs. 



• calcareous tufa: A very porous, commonly fibrous variety of 

 travertine. 



• onyx or onyx marble: A fine-grained, delicately banded variety 

 of travertine. 



• caliche: An impure carbonate deposit formed at or near the 

 surface in porous soils. May be associated with calcareous tufa or 

 other spring deposits. 



