Archie's Rule of Thumb for Mineral Deposit Economics

Archibald M. Bell (1906 - 1991) was a mining geologist and long time VP of Exploration for Noranda.  Later he was a successful consulting geologist.  Bell was an ore finder (Pamour, Timmins and Copper Mountain, Quebec).  He was inducted into the Canadian Mining Hall of Fame in 1995.  Bell is the source of Archie's Rule.

Source:  Canadian Mining Hall of Fame

Several years ago I came across a reference to "Archie's Rule" which is a rule of thumb method for evaluating the economic viability of a mineral deposit.

Simply and elegantly stated:  To be economic a deposit must have a recovered value of twice the all-in operating costs.  This allows for the covering of the capital costs.  The all-in costs includes mining, processing, refining, etc.  It assumes that the mine life will be long enough to extend over multiple metal price cycles.

Clearly not a  NI 43-101 level of evaluation, but a useful tool in evaluating mineral deposits.

The Pink and White Terraces of Lake Rotomahana, NZ

Greetings from Texas,

On April 26, 2016, Robin Wylie of the BBC posted an interesting story on the web about the rediscovery of the Pink and White Terraces on the north island of New Zealand. 
http://www.bbc.com/earth/story/20160427-a-natural-wonder-lost-to-a-volcano-has-been-rediscovered

Geologic map by Ferdinand von Hochstetter (1859) of the Rotamahana or Warm Lake (Left).  The sinter deposits are shown in yellow and are within a volcanic field.  Travel poster for the Pink and White Terraces (Upper right).  Bathers in the warm water of the hot springs (Lower right).

The Pink and White Terraces of Lake Rotomahana and the nearby volcano of Mount Tarawera are hot springs sinter deposits.  The sinter is composed of fine-grained quartz deposited by hydrothermal water of a geothermal field.  The Maori called the terraces taonga which means treasure.  They were also a popular tourist attraction for the well-to-travelers on the 19th century until 1886.  The terraces were "destroyed" by the eruption of Mount Tarawera on June 10, 1886.  The eruption was heard in Christchurch 400 miles away.  The locals, the native New Zealand Maoris, did not see the eruption from their villages.  However, 120 people, mostly Maoris were killed by the fallout of debris from the eruption.

Only one person saw the eruption.  Henry Burt was 7 miles east of the eruption and had a clear view of the volcanic eruption.  He told a journalist the lake looked like a "huge boiling cauldron bubbling in all directions."  After the eruption the terraces were no longed visible.  The New Zealanders had lost a valuable tourist attraction in the violent act of nature.

What we do have are beautiful watercolors of the area by Charles Blomfield, along with black and white photos by various individuals (some hand colored).  The watercolor is below.  The Pink Terraces are in the foreground and the White Terraces are in the distance.

Fortunately, recent scientific research has rediscovered the terraces below the waters and sediment of  Lake Rotomahana.  It is a fantastic story.  It is described in the research articles by C.E.J de Ronde, et.al. in the Journal of Volcanology and Geothermal Research:  Elsevier, volume 314, March 15, 2016.  One of the articles is titled:  The Pink and White Terraces of Lake Rotomahana:  what was their fate after the 1886 Tarawera Rift eruption?  (p.126-141).

 

 

 

Many thanks to Robin Wylie of the BBC for bringing this to the attention of the world and for the research by de Ronde and others for rediscovery the Pink and White Terraces of New Zealand.

 

It is worth your time to take a look at what else is available on the web on this story about the wonders of nature.

 

If you enjoyed this post, please comment.  dle





Geology as Written by John McPhee

This post is to introduce John McPhee to the geologists that have not yet discovered his wonderful writing of "creative non-fiction."  All geologists will gain further knowledge and enjoyment by reading the books by John McPhee.  He has written over thirty books.  Many are about geology.  He travels the world with leading geologists and professors of geology.  One of the main focuses are on development of plate tectonics starting in the 1960's and 1970's.  McPhee is a ,professor at Princeton University and a long time staff writer for the New Yorker magazine.  Many of his writings were first published in the magazine.

A great one to start with is Annals of a Former World published in 1998 and won a Pulitzer Prize in 1999.  It is collection of previously published books:  Basin and Range, In Suspect Terrain, Rising from the Plains, and a new book Crossing the Craton.  His books are published by Farrar, Straus and Giroux, New York.

The first McPhee book that I read was Encounters with the Archdruid (1971).  The book was written in the formative stages of the environmental movement.  There are three parts to this book.  They all involve McPhee and David Brower and three men that supported the development of natural resources in the United States.  Brower was the head of the Sierra Club in the 1950's and 1960's.  He later founded the Friends of the Earth and Earth Island Institute.

McPhee visits Glacier Peak in Washington in the Cascades and a wilderness area.  He visits the area with Charles Park (a well known mining geologist and author of a commonly used college textbook on ore deposits) along with Bowers.  Park is of the opinion that since we have no control of where ore deposits are located, the should be mined even if the White House needed to be moved.

The second meeting and excursion is with Charles Fraser, business man and real-estate developer.  Fraser wants to develop a large housing project on a "wild island" off the coast of Georgia.  Fraser is no-friend to environmentalists and refers to them as "druids."

The final episode is with Floyd Dominy, a longtime commissioner of the Bureau of Reclamation.  Dominy earned his moniker as the archenemy of the druid by overseeing the building of Glen Canyon Dam on the Colorado River.  McPhee is able to get Brower and Dominy to agree to a raft trip through the Grand Canyon of the Colorado River.  Dominy has his eyes on building a dam in the Grand Canyon.  As we know this dam was never built.  The Glen Canyon Dam was built forming Lake Powell.  David Brower states that his greatest failure was not preventing the construction of Glen Canyon Dam.  After that failure, Brower and the Sierra Club became more determined in the efforts to fight large development projects.

Some interesting quotes from Basin and Range:

• "as a general rule material will flow rather than fracture if it is hotter than half its melting point measured from absolute zero."  p. 57
• "The whole of plate tectonics, a story of steady-state violence along boundaries, was being brought to light largely as a result of the development of instruments of war." p. 127  [He is referring to the development of the magnetometer and the detection of "magnetic strips" on the ocean floor which confirmed "Continental Drift and "Plate Tectonics."]

McPhee's "favorite"

• "If by some fiat I had to restrict my writing to one sentence, this is the one I would choose:  The Summit of Mt. Everest is marine limestone."

And possibly my "favorite"

• "With their four-dimensional minds, and in their interdisciplinary ultra verbal way, geologists can wiggle out of almost anything."

Here is a list of the books by John McPhee.  I hope this post encourages you to read one or more of his books.  They are great reads!

A Sense of Where You Are: A Profile of Princeton's Bill Bradley (1965)
The Headmaster: Frank L. Boyden, of Deerfield (1966)
Oranges (1967)
The Pine Barrens (1968)
Levels of the Game (1969)
The Crofter and the Laird (1970)
Encounters with the Archdruid (1971)
The Deltoid Pumpkin Seed (1973)
The Curve of Binding Energy (1974)
Pieces of the Frame (1975)
The Survival of the Bark Canoe (1975)
The John McPhee Reader (1976)
Coming into the Country (1977)
A Roomfull of Hovings and Other Profiles (1979)
Giving Good Weight (1979)
Basin and Range (1981)
In Suspect Terrain (1983)
La Place de la Concorde Suisse (1984)
Heirs of General Practice (1984)
Table of Contents (1985)
Rising from the Plains (1986)
The Control of Nature (1989)
Assembling California (1993)
The Ransom of Russian Art (1994)
The Second John McPhee Reader (1996)
Irons in the Fire (1997, essays)
Annals of the Former World (1998)
The Founding Fish (2002)
Uncommon Carriers (2006)
Silk Parachute (2010)

The Red Sandstone of Heidelberg Castle, Germany

Dear friends and colleagues,

In 2014, I took the Viking River Cruise up the Rhine from Amsterdam to Basal.  The trip went through four countries:  The Netherlands, Germany, France and Switzerland.  It was a great tour of the Rhine River Valley and many ancient castles and even Roman ruins in Cologne.

One of my favorite stops was in Heidelberg were we visited the castle overlooking the Rhine.  The castle is constructed mostly of "Red Sandstone" which displays beautiful cross bedding.  I thought the readers might enjoy seeing some photos and learning a little history of the castle.

The castle was started in 1225 (approximate).  In 1622, the castle was captured by the French during the Thirty Years War.  It was of the first used of explosives to attack and destroy a castle.  The castle suffered damage by several fires.  The Heidelberg has had numerous famous visitors including Martin Luther and Mark Twain.  Twain spent several months in Heidelberg in 1878 when he toured Europe.  His book "A Tramp Abroad" was written in 1880 about his travels in Europe.

“A great and priceless thing is a new interest! How it takes possession of a man! how it clings to him, how it rides him!”   From "A Tramp Abroad"

That is all for now, but if anyone knows the age of the "Red Sandstone" please comment.

dle  Leander, TX

Dikes Exposed - California & Nevada

Dear friends,

It has been too long since I last posted.  My excuse is selling our house in Reno and moving to Leander, Texas (25 north of Austin).  We hope to move into our new house on May 11th.

Going through my geology photos I found a few good pictures of dikes exposed in a road cut on Highway 101 in California west of Malibu.  The last picture is of  basalt flows and dikes cutting Tertiary sedimentary rocks and tuffs in Nevada.

My next BLOG will be about the books by John McPhee and his adventures with leading geologists and other interesting people.

Goodbye for now from the Great State of Texas!

The New Yorker Reporter and Nevada's 1980's Gold Exploration Boom

John Seabrook's article published in 1989 in the New Yorker Magazine is a fascinating read and is worth another visit!  The article is available online at the New Yorker if you are a subscriber.  A link to the article is easy to find using Google.

 

Satellite image of the northern Carlin Trend.  Source:  Google Earth.

I first read the article "A Reporter at Large, Invisible Gold/Gold Mining," in 1989 when it was published. John Seabrook is an easterner.  But in 1989, he visited the northern Nevada gold boom of the 1980's.  The main topics are the mines and towns of Battle Mountain and Carlin along Interstate 80 (I-80).  He spent time with prospectors, geologists, drillers, metallurgists, engineers and others involved in gold mining.

Seabrook had a wonderful adventure and field trips with many of the notables in Nevada gold exploration of the 60's, 70's and 1980's.

Prospectors/claim owners:  Phillip Davis, Andy Hampton, Don Smith, De LaMare.

Geologists:  John Livermore, Alan Coope, Andy Wallace, Peter Galli, Ralph Roberts.

Executives:  Fred Searls (Newmont) Peter Munk (Barrick)

The story starts out at the Owl Club in Battle Mountain. The Owl is a restaurant, bar, casino and hotel.  It was one of the popular establishments in the small town on I-80 and near the railroad tracks.  The main street was formerly US Highway 40.

Roberts and Livermore give Seabrook a first hand summary of the discovery of the Carlin gold deposit in late 1961. Livermore, Coope (both with Newmont) and (Roberts USGS).

I highly recommend this article to all exploration geologists, especially those too young to remember the 1980's.  It is interesting and provides some good insight on successful exploration from some of the best in the business.

dle

Gold Rush, Yukon - Some Photos From My Visits

This post is for the fans of the show Gold Rush on the Discovery Channel,

Last Friday (January 22, 2015) I watched a new episode of the Gold Rush series on the Discovery channel.  I was amazed to see footage of an abandoned gold dredge on Thistle Creek a tributary of the Yukon River.  What was amazing is that I first visited the dredge in 2009.  The dredge is located about 100 kilometers south of Dawson City of Klondike fame.  One of the main characters in the TV series is Tony Beets.  He has purchased the dredge and plans to get it up and running later this year.  He has already refurbished another dredge in the Klondike and it is producing placer gold.  The Thistle dredge only operated for about 5 years during the 1940's.  It will be great to see it brought back to life.  Tony Beets, best of luck with your venture!



Helicopter photo of the Thistle dredge from the TV episode.



Tony Beets flying to Thistle Creek.



Jack Hoffman and some of the Discovery film crew at the Dawson airport in 2010.



Helicopter photos of the gold dredge at Thistle Creek.



Photos of the dredge and visitors that was taken in 2009.  The visitors are geologists (the writer is the third person from the right).  The lower left is looking at the controls in the wheel house and abandoned dredge buckets (lower right).



Small scale placer mining in the White Gold District, Yukon.



Local wildlife and fauna.

A humorous warning on bears in Canada.

Best regards from Reno!