Dust flux, Vostok ice core

Dust flux, Vostok ice core
Two dimensional phase space reconstruction of dust flux from the Vostok core over the period 186-4 ka using the time derivative method. Dust flux on the x-axis, rate of change is on the y-axis. From Gipp (2001).

Wednesday, June 12, 2019

Image of recrystallization of niobium minerals in a carbonatite

From a location that will remain secret for now.

Every so often I get out of my hospital bed and look at some rocks. This image comes from a rock slab I took down to the SEM lab in the Geology Department at the University of Toronto last month some time.

Most people have some idea of how a scanning electron microscope works. Fewer will know about an attachment that many of them have--an energy-dispersive X-ray analysis detector. This device allows for estimation of the elemental composition of a point on a mineral (or a section of whole rock) in a non-destructive fashion.

Blasting a sample with electrons (how the SEM works) ionizes the target area--when it recaptures an electron it releases a quantum of energy in the X-ray spectrum that is characteristic of the element that has been ionized. This allows for the specific elements to be identified and their relative amount quantified.

A second method of analysis involves back-scattered electrons, which create a grey-scale image that results is grey scale, with lighter coloured grains containing heavier elements.


The backscattered electron image above tells me that the white grains have the heaviest elements in them. The X-ray spectrum (not shown) tells me that the heavy element present is niobium. The mineralogy work previously done suggested that the principal niobium-bearing mineral present is pyrochlore--but the x-ray spectrum suggests that many of these grains are actually ferro-columbite (as columbite, but Fe>>Mn), pseudomorphed from pyrochlore.

The gangue minerals are represented by two different regions of grey. The light grey can be shown to be phosphates (mainly apatite) and the darker grey is carbonate (mainly dolomite).

The image above captures something interesting. The columbite grains have begun to lose their distinction from the gangue minerals. Niobium and other heavy elements are being shifted around (the bright white "tendrils" surrounded by black [=silica]) by some late-stage fluid reaction. The x-ray spectrum shows that in addition to Nb, there are rare earth elements present (mainly cerium). This suggests alteration of the columbite to possibly fersmite--although I haven't isolated grains well enough to establish the crystal structure yet.

I wanted to share this because I think this is a spectacular image--from a scientific perspective. From a metallurgical perspective, we would prefer not to see all of those little unrecoverable tendrils of Nb and Ce locked in silica.

Friday, March 29, 2019

How hard is it really to discover gold?

The question of peak gold has been on my mind lately.  I have looked at this problem in the past and  don't have a complete answer, although I am biased towards us being well short of peak gold..


Data from S&P Global Markets
Inflation adjustments calculated from here.

I would like to discuss this diagram. It seems reasonable to assume that an increase in exploration budgets should translate into gold discoveries. A glance at the above graph shows peaks in discoveries associated with the first two peaks in exploration expenses. The last peak in exploration expenses, around 2012, appears to be correlated with a spectacular lack of success on the exploration front, leading to the argument that we have reached (or passed) the time of peak gold.

The devil, however, may be in the details.

There are two confounding details that could change the interpretation of this diagram. The notes on the figure in the original diagram suggest that any new gold discovered on a project is attributed to the year in which the project was discovered. For instance, a junior miner might have discovered a 2 Moz deposit in 1994; and the project is developed over a number of years, probably changing hands in the process. In 2012, the major that now controls it embarks on an exploration program to expand the resource, and discovers a further 3 Moz. That 3 Moz discovery is attributed to 1994, as that is the year the project was discovered (see below).


This is the original version of the figure at the top of this post. The dark blue bars represent gold discovered in 2017, much of which is being attributed earlier years, as those years represent the time of the initial discovery of the projects on which this new gold is found. The small amount of gold attributed to the year 2017 represents new discoveries. If all gold found in 2017 had been attributed to 2017, it would look like a lot more gold was discovered that year--almost 150 Moz, as opposed to the 20-something Moz that appears on the graph instead. Now remember, that this is also true for 2016, and 2015, and 2014, and . . .

This is not an effect that can be easily removed. If it were, we would probably find that a lot of gold was indeed found in the past few years, and the discrepancy between the amount of gold discovered and the money spent on exploration might disappear.

So this graph cannot be used to make the argument that gold is much harder to find than it used to be. It may be used to make the argument that it is harder to find new gold deposits than it used to be, although unless you subtract out the money being spent by majors boosting the resources of existing projects, the graph is still misleading.

And there is another confounding detail that makes even this conclusion difficult to support.

The world of exploration has changed over the last two decades, particularly when it comes to resource definition. It was a lot easier to drill a few holes in 1990 and announce you had a 1 Moz deposit than it is now. It is also a lot easier to expand an existing resource than to define an entirely new one. For this reason, it seems to me that the economic incentives favour spending money on increasing existing resources rather than discovering new ones. At some point in the future this will probably no longer be the case, but it is difficult to predict when that will be; but at that point, there will be a lot more appetite for greenfields exploration again.

In conclusion, I don't consider this graph convincing evidence that gold is in increasingly short supply. It may be running low at a given price, but higher prices will liberate more. I still favour my earlier conclusion of up to 400 deposits in the 1-3 Moz category still to be discovered--and that doesn't include areas like the unexplored parts of Greenland, Antarctica, and the deep ocean.

Friday, November 16, 2018

Anthropocene exhibit at the AGO

Last week I took my son to the AGO to see the Anthropocene exhibition. There were other things I wanted to see as well--mainly the famous staircase.


The Anthropocene Project is about reclassifying our current geological age as one dominated by human activity--at least on and around the Earth's surface. An important goal of the project is to be "revelatory rather than accusatory", and the pictures certainly are a revelation.


The gallery was well attended, mainly by families, and with some of the enriched content (encoded digital goodies that could be seen on your smart phone, or with supplied ipads), the kids that were there remained interested.

I was struck by the printing of some of the images, which almost seemed three-dimensional to my eye.

Unfortunately, there was something of a sour note at the end of the exhibit. At the exit, there was a small exhibit which was only superficially connected to the main exhibition. In fact, I thought it struck a bit of a sour note.


The image shows the concentration of carbon dioxide in the atmosphere. In the same room, there was a survey, where you were permitted to choose one word to summarize your feelings about this display. Of course, it isn't clear if it is about the non-accusatory Anthropocene exhibition, or the short CO2 exhibition. Most of the words you were allowed to select (there were seven) were synonyms for alarmed. There was also one for relaxed and one for suspicious, in case you were a Trump supporter or a conspiracy theorist.

The goal of the Anthropocene project is informing, not alarming. But someone, presumably at the AGO wants you to be alarmed.

There were plenty of other exhibits at the gallery, but we didn't stay much longer. We climbed the staircase.




The top of the staircase ended in a gallery which was closed. Partway down, we entered the modern art exhibit.


A plaque tells us the artist is sealed in the cocoon on the floor.

Sunday, October 21, 2018

Silver is really unpopular

So says my anecdotal evidence.

In China, where silver sells for about four times the world price, it is no surprise that it is unpopular. I tried to give silver jewellery to a girlfriend there--she didn't want it. There was more acceptance of the charming notion of providing a silver spoon as a gift for a baby, as the Chinese do believe that silver draws the toxins out of foods.

I became interested in silver in about 1998, and originally bought it from a local coin shop. Looking for other sources, I found the local United Church held sales in the spring and fall, and jewellery was one of the main topics. Back in those days, nobody was interested in silver, and I bought a lot of old jewellery and the occasional silver spoon, and even a few candlesticks, all at good prices. Some of the jewellery I bought there were listed among my wife's favourite pieces, including an antique piece from Republican times in China, which included a secret pocket for secreting opium.

By around 2004, it began to get more difficult to buy used silver. Groups of young men began to show up at the church sales, aggressively buying up all the silver (and occasionally berating the bemused old ladies administering the sale for not lowering prices when the silver price began to fall). So by about 2006, I had stopped looking for silver at the church sale, and just bought used CDs, games for the kids, and baked goods.

I had been in China for the past few years, but was around for the church sale last week. I decided to see if anything was available in the jewellery section. And there were very few people there, mainly old women, and nobody was interested in the silver. I ended up buying something for my daughter. So this is a more anecdotal evidence of a general lack of interest in silver.

Monday, October 15, 2018

Autumn

This song has been buzzing around in my ear lately.


I'm not sure where this has come from, as it seems to be more of a spring song than an autumn one.

But for the past four years, I have spent autumn and winter in China. And come to think of it, I have spent very little time of any autumn in Canada since about 2007--so maybe it is a response to seeing the autumn colours of Canada for the first time in a long time.




In China, you mostly get yellows. Before China, I spent a lot of time in West Africa, and you get some colour changes in some trees during the dry season, but mostly there is no change