thumbnail

Conditional estimates of the number of podiform chromite deposits

Nonrenewable Resources

By:
DOI: 10.1007/BF02259045

Links

Abstract

A desirable guide for estimating the number of undiscovered mineral deposits is the number of known deposits per unit area from another well-explored permissive terrain. An analysis of the distribution of 805 podiform chromite deposits among ultramafic rocks in 12 subareas of Oregon and 27 counties of California is used to examine and extend this guide. The average number of deposits in this sample of 39 areas is 0.225 deposits per km2 of ultramafic rock; the frequency distribution is significantly skewed to the right. Probabilistic estimates can be made by using the observation that the lognormal distribution fits the distribution of deposits per unit area. A further improvement in the estimates is available by using the relationship between the area of ultramafic rock and the number of deposits. The number (N) of exposed podiform chromite deposits can be estimated by the following relationship: log10(N)=-0.194+0.577 log10(area of ultramafic rock). The slope is significantly different from both 0.0 and 1.0. Because the slope is less than 1.0, the ratio of deposits to area of permissive rock is a biased estimator when the area of ultramafic rock is different from the median 93 km2. Unbiased estimates of the number of podiform chromite deposits can be made with the regression equation and 80 percent confidence limits presented herein. ?? 1994 Oxford University Press.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Conditional estimates of the number of podiform chromite deposits
Series title:
Nonrenewable Resources
DOI:
10.1007/BF02259045
Volume
3
Issue:
3
Year Published:
1994
Language:
English
Publisher location:
Kluwer Academic Publishers
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
200
Last page:
204
Number of Pages:
5