Collections DMGC - Deep Carbon Cycle

Diamond Collections

The diamond collection was registered under the System for Earth Sample Registration (SESAR). Sample registration was ongoing as specimens were added.

SESAR was part of the Integrated Earth Data Alliance (IEDA), hosted at the Lamont Doherty Earth Observatory of Columbia University and funded by LDEO and the National Science Foundation. “SESAR operates a registry that distributes the International Geo Sample Number IGSN. SESAR catalogs and preserves sample metadata profiles, and provides access to the sample catalog via the Global Sample Search.

The IGSN or International GeoSample Number was an alphanumeric code that was assigned to specimens and related sampling features such as drill holes or wells to ensure their unique identification and unambiguous referencing of data generated by the study of samples.” At this point approximately 1600 diamonds had been accessioned into the registry.

SAMPLE REQUESTS

Protocol for Sample Requests and Analysis of Deep Carbon Observatory Diamond Collection

Background

The diamond collection consists of diamonds purchased with DCO funding for the specific purposes of establishing a legacy collection of diamonds that were readily available for researcher to study, as part of a coordinated effort. Details of the samples existing in the collection can be found here.

Sample Requests

Samples may be requested by submitting a research proposal to Steve Shirey and Graham Pearson. The proposal will then be circulated to the Advisory Board who will make a decision on whether to approve the proposed use of the samples. They will use “Best Practice” guidelines recommended by the Society of Mineral Museum Professionals when considering applications.

The collection currently contains diamonds from:

The Juina region, Brazil
Sierra Leone
Catoca, Angola
Zimbabwe
Prairie Creek, USA
Mirny, Russia
Mbuji-Mayi (Miba), DRC

Proposals must contain the following information:

•   Name of Researcher
•   Affiliation
•   Project title
•   Project description, including main aims#
•   Methods to be used, specific names of laboratories and staff involved in analysis
•   Level of sample pre-characterisation required
•   Nature of sample preparation to be used and amount of sample required – no methodological testing that involves > 40% mass loss of the sample will be approved unless exceptional circumstances were demonstrated.
•   Justification for any destructive testing
•   Description of how data will be archived and an statement agreeing to send a copy of all data generated when published
•   A report on the research analysis should be sent to the collection

Other information to be included in the Project Description includes:

The information needed and/or sample does not already exist in the collection files.
The project had merit and a reasonable chance of success and completion.
Plans for dissemination of information in a way that benefits the research and/or public community.

Note: – Samples should be returned to as soon as practically possible and will at all times, remain the property of the collection and the – DCO sample archive should be credited at all times.

N.B. – Individual researchers will be responsible for adhering to correct Kimberley Process procedures for sample shipping, including filing KP documents with the relevant authorities.

Analytical Protocols:

Researchers must adhere as closely as possible to the recommended analytical protocols outlined below:
Individual researchers must pay the cost of diamond plates being made and they will supply recommendations for where this work was done.
All diamonds to be analyzed must be initially characterized by FTIR spectroscopy and cathodoluminscence and the data deposited with, prior to the start of more destructive analytical work.

An idealized flow of analytical work would be:

FTIR spectroscopy to determine nitrogen content and aggregation levels across the plate. If no plate was made it was essential to attempt to obtain a spectrum from a suitable portion of the stone
Raman spectroscopy or X-ray determination of any inclusions
Cutting and polishing of plates or “windows” from agreed portions of diamonds (where practical)
Additional Raman/Xray work
Cathodoluminscence imaging of the diamond plate to image internal structure
EMPA analyses of inclusions or fluids
Carbon isotopic measurement by ion microprobe
More destructive analyses (e.g., laser ablation or cracking of plate to recover diamonds).
All remaining sample materials following analysis were to be returned for storage at DTM Carnegie, where the collection was held.

Advisory Board for Sample Requests:

Graham Pearson (University of Alberta)
Steve Shirey (Carnegie Institution for Science)
Erik Hauri (Carnegie Institution for Science)
Emilie Thomassot (University of Lorainne, France)
Fabrizio Nestola (University of Padua)

DATABASE

The establishment of a database of diamond data, called “DiamondDB” from the literature had been initiated.

A special diamond-specific data template had been created that will allow for the unique data types that diamond researchers collect. It was not yet operational but data from the following papers had been input.

When operational, DiamondDB will function like its siblings PetDB, SedDB, and NavDat. These databases were part of EarthChem which, like SESAR was hosted at LDEO.