622 imbt. CARBONATE POROSITY PROBLEMS [Ch. 33 



FUTURE NEEDED RESEARCH 



The following suggested research approaches to carbonate porosity- 

 are not intended to be a complete list. The more obvious and better 

 known techniques are mentioned as a start on the problem with the 

 full realization that other useful approaches are not mentioned. 



Investigation of Mineral and Rock Properties 



Spectrographs analysis. The identification of minor mineral con- 

 stituents is readily accomplished by the emission spectrograph and 

 flame photometer. Such equipment is expensive and requires con- 

 siderable time to set up; however, once the elements to be determined 

 are grouped, the method is rapid, effective, and relatively inexpensive. 



Petrographic methods. The ordinary petrographic microscope may 

 be employed, crushed grains, polished surfaces, and thin sections being 

 used. Staining and etching techniques as well as methods based on 

 optical properties offer interesting approaches to the general study. 



Thermal analysis. A rapid and accurate method of mineral identi- 

 fication is available through thermal studies. This technique may be 

 applied to carbonate rocks to determine their mineralogical composi- 

 tion. 



Electron micrography. The possible use of the electron microscope 

 should be investigated ; however, new techniques will probably have to 

 be developed to adapt this method to mineral identification. The 

 method will probably find more utility in studies of the details of 

 orientation and distribution which could furnish direct application to 

 studies of chert and development of porosity. 



Heavy liquids and centrifuge. Mineral separation can be accom- 

 plished by simple gravity differentiation through the use of heavy 

 liquids or the centrifuge. 



Quantitative chemical analysis. Chemical analyses are expensive, 

 and they find limited use as a check against other more rapid and less 

 costly methods. 



Insoluble residues. A large variety of substances, both mineral and 

 organic, are relatively insoluble in dilute hydrochloric acid. The in- 

 soluble residue consists mainly of chert, opal, clay, silt, and sand, with 

 non-mineral organic constituents in recognizable amounts. In all 

 probability, clays are partly altered or destroyed in residue prepara- 

 tions ; nevertheless some value may be gained from their investigation, 

 and this should certainly be included in a general program. Most in- 

 soluble residue work has been done to expedite stratigraphic correlation 



