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Extensions to the demonstration of Gy's formula

D. Francois-Bongarcon
Extensions to the demonstration of Gy's formula (in Quality assurance, continuous quality improvement and standards in mineral resource estimation, Marcel A. Vallee (editor) and Alastair J. Sinclair (editor))
Exploration and Mining Geology (April 1998) 7 (1-2): 149-154


This paper discusses the fundamental question, "what is an adequate sample size?" in the light of recent developments regarding parameters of Gy's well-known formula for predicting sampling variance. New understanding of the granulometric factor, g, and the liberation factor, I, have significant impact on the results of calculations involving Gy's equation. For the granulometric factor, justifications are given as to why nominal comminution size should always be reported as P95 (i.e. the screen size rejecting 95% of the mass). A small but important change in the model to estimate the liberation factor makes the difference between a predictive formula that works and one that does not. Other parameters and considerations regarding their practical implementation are commented upon in the light of the author's experience.

ISSN: 0964-1823
Serial Title: Exploration and Mining Geology
Serial Volume: 7
Serial Issue: 1-2
Title: Extensions to the demonstration of Gy's formula
Title: Quality assurance, continuous quality improvement and standards in mineral resource estimation
Author(s): Francois-Bongarcon, D.
Author(s): Vallee, Marcel A.editor
Author(s): Sinclair, Alastair J.editor
Affiliation: Mineral Resource Development, San Mateo, CA, United States
Affiliation: Geoconseil Marcel Vallee, Sainte-Foy, QC, Canada
Pages: 149-154
Published: 199804
Text Language: English
Publisher: Canadian Institute of Mining, Metallurgy and Petroleum, Montreal, QC, Canada
Meeting name: Geological Society of CIM symposium on Quality control of resource estimation; an ISO perspective
Meeting location: Montreal, QC, CAN, Canada
Meeting date: 19981998
References: 13
Accession Number: 2000-074373
Categories: Economic geology, general, deposits
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: University of British Columbia, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200023
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