[ RadSafe ] Red Sand

Sun Mar 24 14:13:09 CDT 2013

Mike and Dan,

Could it be staurolite: http://en.wikipedia.org/wiki/Staurolite?

DuPont makes a "Coarse Staurolite Sand": http://www2.dupont.com/Titanium_Technologies/en_US/products/staurolite/index.html for sand blasting.

Jerry

________________________________

The statements and opinions expressed herein are my responsibility; no one else (certainly not my employer) is responsible, but I still reserve the right to make mistakes.

Gerald A. Falo, Ph.D., CHP
Army Institute of Public Health - Health Physics Program
jerry.falo at us.army.mil
410-436-4852
DSN: 584-4852

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Cowie, Michael I
Sent: Sunday, March 24, 2013 2:14 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Red Sand

Thanks Dan, but perhaps I was being a bit obtuse with information on my earlier email. The material has been found spread over an area and appears to have been used in an uncontrolled way in an abrasive blasting method. I have discovered that this area was used to overhaul and refurbish a large section of pipework, and included blasting/hydro testing. I have some pictures of the sand (unfortunately cannot append on the list), and also XRF/XRD analysis which indicates:

Si 20.9%
Fe 14.9%
Al 4.7%
Ca 3.7%
Mg 1.7%
Na 0.8%
Ti 0.7%
Mn 0.5%
K 0.4%
S 0.3%
Cl 0.1%
Zr 0.09%

Almandine-(Mg0.6Fe2.4)Al2(SiO4)3        47 Wt%
Quartz-SiO2                             44 Wt%
Calcite-CaCO3                           6 Wt%
Microcline-KAlSi3O8                     3 Wt%

Looking at the U figure in the data provided it gives 14.8 +/- 3.7 ug/g. The Th iis 181.7 +/- 2.9 ug/g.

The material is definitely alien to the place where it has ended up, but not yet been able to track down where it came from.

I also have a nice image of the spread of the contamination over the area using the RadSurvey gamma mapping equipment.

Mike

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Dan McCarn
Sent: Sunday, March 24, 2013 8:50 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Red Sand

Dear Michael:

I think it is highly unlikely to be garnet.

The described material is far more likely to be a red zircon sand, hard and abrasive, and can be concentrated in beach and stream placers in & around igneous and metamorphic terrains because it does not tend to weather. From memory, it can contain up to about 1% uranium. Zircon is a zirconium silicate for which the zircon can be replaced with a significant amount of rare-earth elements including thorium as well as uranium.

For a zircon containing 0.25% U-nat, that would amount to an activity of about 30 Bq/g for each member of the decay chain.  I have seen and mapped Cretaceous beach placers in the Trinidad sandstone of Colorado / New Mexico for many kilometers.  Undoubtedly, the beach sand was derived from the ancestral Rockies, full of granite with abundant zircon.
 Long-shore drift concentrated the beach placers giving them a significantly higher gamma "kick" with borehole-logging tools than would be expected, and were occasionally mistaken for "roll-front" type sandstone uranium deposits, but are of no economic interest (for uranium) due to the chemically inert nature of zircon. Neither uranium nor thorium would leach from zircon sands.

See http://en.wikipedia.org/wiki/Zircon

"Zircon occurs in many colors, including red, pink, brown, yellow, hazel, or black. It can also be colorless. The color of zircons can sometimes be changed by heat treatment. Depending on the amount of heat applied, colorless, blue, or golden-yellow zircons can be made. In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years, if the crystal has sufficient trace elements to produce color centers. Color in this red or pink series is annealed in geological conditions above the temperature about 350 °C."

"Zircon is a common accessory to trace mineral constituent of most granite<http://en.wikipedia.org/wiki/Granite>
 and felsic <http://en.wikipedia.org/wiki/Felsic> igneous rocks. Due to its hardness, durability and chemical inertness, zircon persists in sedimentary deposits and is a common constituent of most sands. Zircon is rare within mafic rocks <http://en.wikipedia.org/wiki/Mafic_rock> and very rare within ultramafic <http://en.wikipedia.org/wiki/Ultramafic> rocks aside from a group of ultrapotassic intrusive rocks<http://en.wikipedia.org/wiki/Ultrapotassic_igneous_rocks> such as kimberlites <http://en.wikipedia.org/wiki/Kimberlite>, carbonatites, and lamprophyre, where zircon can occasionally be found as a trace mineral owing to the unusual magma genesis of these rocks."

"Zircon forms economic concentrations within heavy mineral sands ore deposits <http://en.wikipedia.org/wiki/Heavy_mineral_sands_ore_deposits>,
within certain pegmatites <http://en.wikipedia.org/wiki/Pegmatite>, and within some rare alkaline volcanic rocks, for example the Toongi Trachyte, Dubbo, New South Wales Australia[9]<http://en.wikipedia.org/wiki/Zircon#cite_note-9> in association with the zirconium-hafnium minerals eudialyte<http://en.wikipedia.org/wiki/Eudialyte> and armstrongite."

Dan ii

Dan W McCarn, Geologist
108 Sherwood Blvd
Los Alamos, NM 87544-3425
+1-505-672-2014 (Home – New Mexico)
+1-505-670-8123 (Mobile - New Mexico)
HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com

On Sat, Mar 23, 2013 at 10:51 PM, Cowie, Michael I <michael.cowie at aramco.com
> wrote:

> Abrasive Sand/grit
>
> Also recently encountered some red coloured fine sand, it has been 
> suggested the material is "Garnet". Activity concentration is in the 
> order of 30Bq/g (Total activity), and have measured gamma dose rates 
> of in excess of 3microSiverts/hr from the material. A few years ago we 
> ceased using abrasive sands/silica for blasting/preparation ops due to 
> health related issues (silicosis) and the replacement material is a 
> type of black grit (a trade name I have seen is EuroGrit, but there 
> are others). This also has slightly enhanced activity levels but only 
> around 1Bq/g. So it came as a bit of a shock to find this material, 
> particularly with such enhanced activity levels and associated gamma dose-rate.
>
> Again a couple of questions:
>
> Are the activity concentrations in the "granet" or Rad Sand typical?
> Are there standards to which suppliers should adhere?
>
> I am pretty certain that this material if shipped now would trigger 
> alarms at ports of entry if exported.
>
> Mike
>
>
>
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