Limestone Exploration:
Identify Calcite, Dolomite, and Clay
 First in Full Range PDA Spectrometer, Spectroradiometer and Spectrophotometer Systems
1 Canal Street  ◊  Unit B1
Lawrence, MA 01840  USA
Tel: 978 687-1833  ◊  Fax: 978 945-0372
Email:
info@spectralevolution.com


Copyright © 2012 Spectral Evolution, Inc
Limestone is used in a variety of commercial and industrial products,
from Portland cement  to aggregate (gravel) to powdered limestone
for steel processing, to decorative marble. During exploration
geologists often must identify the minerals typically found in
limestone, including calcite, dolomite, quartz, pyrite, and clay. Calcite
and dolomite are the key ingredients in commercially valuable
limestone deposits and it is often difficult to distinguish these
minerals from clays in the mixture.

Classification of limestone:
  • Calcite limestone - more than 90% calcite and 10 % dolomite
  • Dolomitic Limestone - calcite 50-90% with dolomite 10-50%
  • Calcite dolomite - calcite 10-50% and dolomite 50-90%
  • Dolomite - calcite less than 10% with dolomite more than 90%

With the
oreXpress field spectrometer, scans of prospective
limestone deposits can be taken in the field and identified for the
different minerals using
EZ-ID mineral identification software.

The oreXpress is lightweight, rugged and reliable. Throw it in a
backpack with its lithium-ion batteries and you have around 4 hours
of scanning from each battery. With all solid state photodiode array
design, there are no moving optical parts for breakage or
misalignment.

With its high resolution and great sensitivity, the oreXpress delivers
clear and accurate scans that EZ-ID can identify by marching to two
libraries of 1600 spectra for 600 minerals. Each mineral has a
distinctive spectra. In our limestone sample, kaolinite clay is
differentiated by the doublet absorption features near 1400nm and
2200nm. Calcite and dolomite share similar features but can be
separately identified. Dolomite has prominent features at 1858, 1978,
and 2320nm. Calcite has features at 1875, 1995, and 2330nm.
SPECTRAL EVOLUTION CORPORATE LOGO - FIRST IN UV-VIS-NIR SPECTROMETER, SPECTRORADIOMETER AND SPECTROPHOTOMETER PRODUCTS
 First in Full Range PDA Spectrometer, Spectroradiometer and Spectrophotometer Systems
Dolomite identified by EZ-ID mineral identification
software.
Calcite identified by EZ-ID mineral identification
software.
Kaolinitie identified by EZ-ID mineral identification
software. Note the two doublets.