Featured Research

from universities, journals, and other organizations

Chocolate and diamonds: Why volcanoes could be 'a girl's best friend'

Date:
May 16, 2012
Source:
University of Southampton
Summary:
Scientists have discovered a previously unrecognized volcanic process, similar to one that is used in chocolate manufacturing, which gives important new insights into the dynamics of volcanic eruptions. The scientists investigated how a process called ‘fluidized spray granulation’ can occur during kimberlite eruptions to produce well-rounded particles containing fragments from the Earth’s mantle, most notably diamonds.

Pelletal lapilli. Diamond in kimberlite rock, Jwaneng Diamond Mine, Botswana.
Credit: Image courtesy of University of Southampton

Scientists from the University of Southampton have discovered a previously unrecognised volcanic process, similar to one that is used in chocolate manufacturing, which gives important new insights into the dynamics of volcanic eruptions.

The scientists investigated how a process called 'fluidised spray granulation' can occur during kimberlite eruptions to produce well-rounded particles containing fragments from Earth's mantle, most notably diamonds. This physical process is similar to the gas injection and spraying process used to form smooth coatings on confectionary, and layered and delayed-release coatings in the manufacture of pharmaceuticals and fertilisers.

Kimberlite volcanoes are the primary source of diamonds on Earth, and are formed by gas-rich magmas from mantle depths of over 150 km. Kimberlite volcanism involves high-intensity explosive eruptions, forming diverging pipes or 'diatremes', which can be several hundred metres wide and several kilometres deep. A conspicuous and previously mysterious feature of these pipes are 'pelletal lapilli ' -- well-rounded magma coated fragments of rock consisting of an inner 'seed' particle with a complex rim, thought to represent quenched magma.

These pelletal lapilli form by spray granulation when kimberlite magma intrudes into earlier volcaniclastic infill close to the diatreme root zone. Intensive degassing produces a gas jet in which the seed particles are simultaneously fluidised and coated by a spray of low-viscosity melt.

In kimberlites, the occurrence of pelletal lapilli is linked to diamond grade (carats per tonne), size and quality, and therefore has economic as well as academic significance.

Dr Thomas Gernon, Lecturer in Earth Science at the University of Southampton, says: "The origin of pelletal lapilli is important for understanding how magmatic pyroclasts are transported to the surface during explosive eruptions, offering fundamental new insights into eruption dynamics and constraints on vent conditions, notably gas velocity."

"The ability to tightly constrain gas velocities is significant, as it enables estimation of the maximum diamond size transported in the flow. Gas fluidisation and magma-coating processes are also likely to affect the diamond surface properties."

Dr Gernon and colleagues studied two of the world's largest diamond mines in South Africa and Lesotho. In the Letseng pipe in Lesotho, pelletal lapilli have been found in association with concentrations of large diamonds (up to 215 carat), which individually can fetch up to tens of millions of pounds. Knowledge of flow dynamics will inform models of mineral transport, and ultimately could improve resource assessments.

Dr Gernon, who is based at the National Oceanography Centre at Southampton's waterfront campus, says: "This multidisciplinary research, incorporating Earth sciences, chemical and mechanical engineering, provides evidence for fluidised granulation in natural systems which will be of considerable interest to engineers and chemical, pharmaceutical and food scientists who use this process routinely. The scale and complexity of this granulation process is unique, as it has not previously been recognised in natural systems."


Story Source:

The above story is based on materials provided by University of Southampton. Note: Materials may be edited for content and length.


Journal Reference:

  1. T.M. Gernon, R.J. Brown, M.A. Tait, T.K. Hincks. The origin of pelletal lapilli in explosive kimberlite eruptions. Nature Communications, 2012; 3: 832 DOI: 10.1038/ncomms1842

Cite This Page:

University of Southampton. "Chocolate and diamonds: Why volcanoes could be 'a girl's best friend'." ScienceDaily. ScienceDaily, 16 May 2012. <www.sciencedaily.com/releases/2012/05/120516093202.htm>.
University of Southampton. (2012, May 16). Chocolate and diamonds: Why volcanoes could be 'a girl's best friend'. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2012/05/120516093202.htm
University of Southampton. "Chocolate and diamonds: Why volcanoes could be 'a girl's best friend'." ScienceDaily. www.sciencedaily.com/releases/2012/05/120516093202.htm (accessed October 20, 2014).

Share This



More Earth & Climate News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Powerful Hurricane Gonzalo Heads to Bermuda

Raw: Powerful Hurricane Gonzalo Heads to Bermuda

AP (Oct. 17, 2014) Hurricane Gonzalo pounded Bermuda with wind and heavy surf on Friday, bearing down on the tiny British territory as a powerful Category 3 storm that could raise coastal seas as much as 10 feet. (Oct. 17) Video provided by AP
Powered by NewsLook.com
So, Kangaroos Didn't Always Hop

So, Kangaroos Didn't Always Hop

Newsy (Oct. 16, 2014) Researchers believe an extinct kangaroo species weighed 500 pounds or more and couldn't hop. Video provided by Newsy
Powered by NewsLook.com
Hurricane Gonzalo Is A Category 4 And Heading To Bermuda

Hurricane Gonzalo Is A Category 4 And Heading To Bermuda

Newsy (Oct. 16, 2014) Powerful hurricane could hit Bermuda this weekend, and even if it misses it will likely do some damage. Video provided by Newsy
Powered by NewsLook.com
The Largest Volcano In Centuries Is Spewing Toxic Gas

The Largest Volcano In Centuries Is Spewing Toxic Gas

Newsy (Oct. 16, 2014) One of the largest volcanic eruptions in centuries is occurring on Iceland. The volcano Bardarbunga is producing high levels of sulfur dioxide. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins