Ann: Deep Drilling Hits More Copper at Storm, page-48

I thought you guys might like to share this report about sedimentary hosted copper deposits.

There are three sub types, with quite different properties. ATM I dont think we have been told which type, or even if any of these types apply, so maybe it is all a bit academic so far.

Subtypes
Three subtypes of sediment-hosted copper deposits with significant differences in tonnage and copper grade are recognized: reduced-facies Cu (56 deposits), redbed Cu (32 deposits),and Revett Cu (15 deposits). The three types differ in the strength and efficiency of the reductant at the site of deposition.
In reduced-facies deposits, the reductant is a marine or lacustrine fine-grained sediment containing abundant organic matter.
In redbed deposits, the reductant is more weakly distributed, represented by patches of organic debris in sandstone.
In Revett Cu deposits, the reductant is broad and diffuse and in some Phanerozoic deposits can be shown to be gaseous or liquid hydrocarbon, or sulfide-rich sour gas.

Median tonnages are 2.0 Mmt for 35 redbed deposits, and 33 Mmt for 58 reduced facies deposits, and 14 Mmt for 11 Revett deposits. This difference between Redbed and reduced facies is significant at the one percent level, and between Redbed and Revett at the one percent level (such a difference could happen by chance less than one percent of thetime).

Median copper grades are 1.6 percent for redbed and 2.3 percent for reduced facies deposits. This difference is significant the five percent level. Median copper grade for Revett Cu deposits 0.79 percent, and median silver grade is 31 grams per ton

This from https://pubs.usgs.gov/of/2003/of03-107/of03-107.pdf

Recall too that there are another types of copper deposit which can exist in sediments but are classified differently - IOCG (Olympic Dam), ISCG (Eloise) and SEDEX (Mt Isa) are examples.

All are classified by the reactant which replaces the copper from the circulating waters, except for SEDEX in which the copper sulphides are deposited in the sediments as they form by an active under sea volcano. SEDEX is also unusual because deposits are being formed as we speak at underwater sites - no doubt they will one day be mined - lets see what the wokes awaken to on that.

For interest only - may not apply to Storm Deposits.