LITHOGEOCHEMISTRY

The most aggressive fusion technique employs a lithium metaborate/ tetraborate fusion for whole rock analysis.

Actlabs performs fusions using a robotic system, which provides a fast fusion of the highest quality in the industry. The resulting molten bead is rapidly digested in a weak nitric acid solution. The fusion ensures that the entire sample is dissolved. It is only with this attack that major oxides including SiO2, refractory minerals (i.e. zircon, sphene, monazite, chromite, gahnite, etc.), REE and other high field strength elements are put into solution. High sulphide-bearing rocks may require different treatment but can still be adequately analyzed. Analysis is by ICP-OES and ICP-MS. Quality of data is exceptional and can be used for the most exacting applications. Values on replicates and standards are provided at no cost, as well as REE chondrite plots. Eu determinations are semi-quantitative in samples having extremely high Ba concentrations (> 5 %). Although intended primarily for un-mineralized samples, mineralized samples can also be analyzed; however, data may be semi-quantitative for chalcophile elements (Ag, As, Bi, Co, Cu, Mo, Ni, Pb, Sb, Sn, W and Zn).

Samples are prepared and analyzed in a batch system. Each batch contains a method reagent blank, certified reference material and 6% replicates. Samples are mixed with a flux of lithium metaborate and lithium tetraborate and fused in an induction furnace. The molten melt is immediately poured into a solution of 5% nitric acid containing an internal standard, and mixed continuously until completely dissolved (~45 minutes). The samples are run for major oxides and selected trace elements (4B) on a combination simultaneous/sequential Thermo Jarrell-Ash ENVIRO II ICP or a Varian Vista 735 ICP. Calibration is performed using 14 prepared USGS and CANMET certified reference materials. One of the 14 standards is used during the analysis for every group of ten samples.

Totals should be between 98.5% and 101%. If results come out lower, samples are scanned for base metals. Low reported totals may indicate sulphate being present or other elements like Li which won’t normally be scanned for. Samples with low totals however are automatically re-fused and reanalyzed.

Fusion ICP

OxideDetection Limit (%)
Al2O30.01
CaO0.01
Fe2O30.01
K2O0.01
MgO0.01
MnO0.001
Na2O0.01
P2O50.01
SiO20.01
TiO20.001
Loss on Ignition0.01

Trace Elements

ElementDetection Limit (ppm)
Ba2
Be1
Sc1
Sr2
V5
Y2
Zr4

Code 4B options:

Code 4B1 : recommended for accurate levels of base metals (Cu, Pb, Zn, Ni and Ag) .

Code 4B-INAA : recommended for As, Sb, high W >100 ppm and Cr > 1,000 ppm.

Samples fused under code 4B2 are diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP/MS. Three blanks and five controls (three before the sample group and two after) are analyzed per group of samples. Duplicates are fused and analyzed every 15 samples. Instrument is recalibrated every 40 samples.

Elements and Detection Limits (ppm)

ElementDetection LimitUpper Limit
Hf0.21,000
Ho0.11,000
In0.2200
La0.12,000
Lu0.041,000
Mo2100
Nb11,000
Nd0.12,000
Ni2010,000
Pb510,000
Pr0.51,000
Rb21,000
Sb0.5200
Sm0.11,000
ElementDetection LimitUpper Limit
Sn11,000
Sr210,000
Ta0.1500
Tb0.11,000
Th0.12,000
Tl0.11,000
Tm0.051,000
U0.11,000
V55,000
W15,000
Y11,000
Yb0.11,000
Zn3010,000
Zr510,000

Typical ICP/MS Standards Analysis (119 measurements)

ElementW2Cert.
Y2124
Zr9994
Nb7.57.9
Mo0.70.6
Ag<0.50.05
In<0.2-
Sn<0.5-
Sb0.780.79
Cs0.950.99
Ba164182
La11.311.4
ElementW2Cert.
Yb2.0620.5
Lu0.330.33
Hf2.642.56
Ta0.50.5
W<0.20.3
Tl0.10.2
Pb89.3
Bi<0.050.03
Th2.32.5
U0.490.53

4B2-STD options:

4B2-STDQuant: Although intended primarily for unmineralized samples, mineralized samples can be analyzed. However data may be semiquantitative for chalcophile elements (Ag, As, Bi, Co, Cu, Mo, Ni, Pb, Sb, Sn, W and Zn). A 1 g sample is digested with aqua regia and diluted to 250 ml volumetrically. Appropriate international reference materials for the metals of interest are digested at the same time. The samples and standards are analyzed on a Varian Vista 735 or a Thermo ICAP 6500 ICP.

Code 4B1 : recommended for accurate levels of base metals (Cu, Pb, Zn, Ni and Ag) .

Code 4B-INAA : recommended for As, Sb, high W >100 ppm and Cr > 1,000 ppm

Code 5D: recommended for Sn >50 ppm.

Samples fused under code 4B2 are diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP/MS. Three blanks and five controls (three before the sample group and two after) are analyzed per group of samples. Duplicates are fused and analyzed every 15 samples. Instrument is recalibrated every 40 samples.

Elements and Detection Limits (ppm)

ElementDetection LimitUpper Limit
Ag0.5100
As52,000
Ba3300,000
Bi0.12,000
Ce0.053,000
Co11,000
Cr2010,000
Cs0.11,000
Cu1010,000
Dy0.011,000
Er0.011,000
Eu0.0051,000
Ga1500
Gd0.011,000
ElementDetection LimitUpper Limit
Hf0.11,000
Ho0.011,000
In0.1200
La0.052,000
Lu0.0021,000
Mo2100
Nb0.21,000
Nd0.052,000
Ni2010,000
Pb510,000
Pr0.011,000
Sb0.2200
Sm0.011,000
ElementDetection LimitUpper Limit
Sn11,000
Sr210,000
Ta0.01500
Tb0.011,000
Th0.052,000
Tl0.051,000
Tm0.0051,000
U0.011,000
V55,000
W0.55,000
Y0.55,000
Yb0.011,000
Zn3010,000
Zr110,000

Typical ICP/MS Standards Analysis (119 measurements)

ElementW2Cert.
V256262
Cr9093
Co4444
Ni6770
Cu105103
Zn7277
Ga1820
Ge21
As<51.24
Rb2020
Sr193194
ElementW2Cert.
Y2124
Zr9994
Nb7.57.9
Mo0.70.6
Ag<0.50.05
In<0.2-
Sn<0.5-
Sb0.780.79
Cs0.950.99
Ba164182
La11.311.4
ElementW2Cert.
Ce2424
Pr2.55.9?
Nd1414
Sm3.383.25
Eu1.11.1
Gd3.53.6
Tb0.620.63
Dy3.83.8
Ho0.760.76
Er2.32.5
Tm0.320.38
ElementW2Cert.
Yb2.0620.5
Lu0.330.33
Hf2.642.56
Ta0.50.5
W<0.20.3
Tl0.10.2
Pb89.3
Bi<0.050.03
Th2.32.5
U0.490.53

4B2-Research options:

4B2-ResearchQuant: Although intended primarily for unmineralized samples, mineralized samples can be analyzed. However data may be semiquantitative for chalcophile elements (Ag, As, Bi, Co, Cu, Mo, Ni, Pb, Sb, Sn, W and Zn).

Code 4B1 : recommended for accurate levels of base metals (Cu, Pb, Zn, Ni and Ag) .

Code 4B-INAA : recommended for As, Sb, high W >100 ppm and Cr > 1,000 ppm.

Code 5D: recommended for Sn >50 ppm.

A combination of packages 4B (lithium metaborate/tetraborate fusion ICP whole rock) and 4B2 (trace element ICP-MS)

Fused sample is diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP/MS. Calibration is performed using 10 synthetic calibration standards. A set of 10 certified reference material is run before and after every batch of samples. Duplicates are fused and analyzed every 17 samples. Instrument is recalibrated every 2 trays of samples.

Fusion ICP

OxideDetection LImit (%)
Al2O30.01
CaO0.01
Fe2O30.01
K2O0.01
MgO0.01
MnO0.001
Na2O0.01
P2O50.01
SiO20.01
TiO20.001
Loss on Ignition0.01

Trace Elements and Detection Limits (ppm)

ElementDetection LimitUpper LimitReported By
Ag0.5100ICP/MS
As52,000ICP/MS
Ba2500,000ICP
Be1-ICP
Bi0.42,000ICP/MS
Ce0.13,000ICP/MS
Co11,000ICP/MS
Cr2010,000ICP/MS
Cs0.51,000ICP/MS
Cu1010,000ICP/MS
Dy0.11,000ICP/MS
Er0.11,000ICP/MS
Eu0.051,000ICP/MS
Ga1500ICP/MS
Gd0.11,000ICP/MS
Ge1500ICP/MS
Hf0.21,000ICP/MS
Ho0.11,000ICP/MS
In0.2200ICP/MS
La0.12,000ICP/MS
Lu0.011,000ICP/MS
Mo2100ICP/MS
Nb11,000ICP/MS
ElementDetection LimitUpper LimitReported By
Nd0.12,000ICP/MS
Ni2010,000ICP/MS
Pb510,000ICP/MS
Pr0.051,000ICP/MS
Rb21,000ICP/MS
Sb0.5200ICP/MS
Sc1-ICP
Sm0.11,000ICP/MS
Sn11,000ICP/MS
Sr210,000ICP
Ta0.1500ICP/MS
Tb0.11,000ICP/MS
Th0.12,000ICP/MS
Tl0.11,000ICP/MS
Tm0.051,000ICP/MS
U0.11,000ICP/MS
V510,000ICP
W15,000ICP/MS
Y110,000ICP
Yb0.11,000ICP/MS
Zn3010,000ICP/MS
Zr210,000ICP

4Litho options:

4LithoQuant: Although intended primarily for unmineralized samples, mineralized samples can be analyzed. However data may be semiquantitative for chalcophile elements (Ag, As, Bi, Co, Cu, Mo, Ni, Pb, Sb, Sn, W and Zn).

Code 4B1 : recommended for accurate levels of base metals (Cu, Pb, Zn, Ni and Ag) .

Code 4B-INAA : recommended for As, Sb, high W >100 ppm and Cr > 1,000 ppm.

Code 5D: recommended for Sn >50 ppm.

A combination of packages 4B (lithium metaborate/tetraborate fusion ICP whole rock) and 4B2 (trace element ICP-MS).

Fused sample is diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP-MS. Calibration is performed using 10 synthetic calibration standards. A set of 10 certified reference material is run before and after every batch of samples. Duplicates are fused and analyzed every 17 samples. Instrument is recalibrated every 2 trays of samples.

Fusion ICP

OxideDetection Limit (%)
SiO20.01
Al2O30.01
Fe2O30.01
MgO0.01
MnO0.001
CaO0.01
TiO20.001
Na2O0.01
K2O0.01
P2O50.01
Loss on Ignition0.01

Trace Elements and Detection Limits (ppm)

ElementDetection LimitUpper LimitReported By
Nd0.052,000ICP/MS
Ni2010,000ICP/MS
Pb510,000ICP/MS
Pr0.011,000ICP/MS
Rb11,000ICP/MS
Sb0.2200ICP/MS
Sc1-ICP/MS
Sm0.011,000ICP/MS
Sn11,000ICP/MS
Sr210,000ICP
Ta0.01500ICP/MS
Tb0.011,000ICP/MS
Th0.052,000ICP/MS
Tl0.051,000ICP/MS
Tm0.0051,000ICP/MS
U0.011,000ICP/MS
V510,000ICP
W0.55,000ICP/MS
Y0.510,000ICP/MS
Yb0.011,000ICP/MS
Zn3010,000ICP/MS
Zr110,000ICP/MS

4Lithoresearch – Options

4LithoResearchQuant: Although intended primarily for unmineralized samples, mineralized samples can be analyzed. However data may be semiquantitative for chalcophile elements (Ag, As, Bi, Co, Cu, Mo, Ni, Pb, Sb, Sn, W and Zn).

Code 4B1 : recommended for accurate levels of base metals (Cu, Pb, Zn, Ni and Ag) .

Code 4B-INAA : recommended for As, Sb, high W >100 ppm and Cr > 1,000 ppm.

Code 5D: recommended for Sn >50 ppm.

Add-Ons:

A 0.25 g sample is digested with four acids beginning with hydrofluoric, followed by a mixture of nitric and perchloric acids, heated using precise programmer controlled heating in several ramping and holding cycles which takes the samples to dryness. After dryness is attained, samples are brought back into solution using hydrochloric acid. With this digestion certain phases may be only partially solubilized. These phases include zircon, monazite, sphene, gahnite, chromite, cassiterite, rutile and barite. Ag greater than 50 ppm and Pb greater than 5,000 ppm should be assayed as high levels may reprecipitate. Only sulphide sulfur will be solubilized.

In-lab standards (traceable to certified reference materials) or certified reference materials are used for quality control.

Samples are analyzed using a Varian Vista 735 ICP.

Elements and Detection Limits (ppm)

ElementDetection LimitUpper Limit
Ag0.3100
Cd0.52,000
Cu110,000
Ni110,000
Pb55,000
S0.001%20%
Zn110,000

INAA (Instrumental Neutron Activation Analysis) is an analytical technique dependent on measuring gamma radiation induced in the sample by irradiation with neutrons. The primary source of neutrons for irradiation is usually a nuclear reactor. Each activated element emits a “fingerprint” of gamma radiation which can be measured and quantified. Routine multi-element analyses by INAA are performed on practically any material from the smallest sample which can be weighed accurately to very large samples.

A 30g aliquot, if available, is encapsulated in a polyethylene vial and irradiated along with flux wires at a thermal neutron flux of 7 x 10 12 ncm-2 s-1. After a 7-day period to allow Na-24 to decay the samples are counted on a high purity Ge detector with resolution of better than 1.7 KeV for the 1332 KeV Co-60 photopeak. Using the flux wires and control standards, the decay-corrected activities are compared to a calibration developed from multiple certified international reference materials. For values exceeding the upper limits, assays are recommended. One standard is run for every 11 samples. One blank is analyzed per work order. Duplicates are analyzed when sample material is available.

Elements and Detection Limits (ppm)

ElementDetection LimitUpper Limit
As0.510,000
Au2 ppb30,000 ppb
Br0.55000
Ce310,000
Co110,000
Cr5100,000
Cs110,000
Eu0.210,000
Hf15000
Ir5 ppb10,000
La0.510,000
Lu0.0510,000
ElementDetection LimitUpper Limit
Mo510,000
Nd510,000
Rb2010,000
Sb0.210,000
Se310,000
Sm0.110,000
Ta0.510
Tb0.510,000
Th0.210,000
U0.510,000
W110,000
Yb0.210,000

Reference:

Hoffman, E.L., 1992. Instrumental Neutron Activation in Geoanalysis. Journal of Geochemical Exploration, volume 44, pp. 297-319.

For quantitative values of chalcophile elements

X-ray fluorescence (XRF) spectroscopy method is used as industry standard for the determination of the major and some trace elements. This method has a rapid turnaround time and offers one of the best levels accuracy and precision of any multi elemental geochemistry package.

To minimize the matrix effects of the samples, the heavy absorber fusion technique of Norrish and Hutton (1969, Geochim. Cosmochim. Acta, volume 33, pp. 431-453) are used for major element (oxide) analysis.  Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2, S and other volatiles, can be determined from the weight loss after roasting the sample at 1000°C for 2 hours. The fusion disk is made by mixing a 0.75 g equivalent of the roasted sample with 9.75 g of a combination of lithium metaborate and lithium tetraborate with lithium bromide as a releasing agent. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced wavelength dispersive XRF

 The intensities are then measured and the concentrations are calculated against the standard G-16 provided by Dr. K. Norrish of CSIRO, Australia.  Matrix corrections were done by using the oxide alpha – influence coefficients provided also by K. Norrish. In general, the limit of detection is about 0.01 wt% for most of the elements.

Oxides and Detection Limits (%)

OxideDetection
Al2O30.01
CaO0.01
Cr2O30.01
Co3O40.005
CuO0.005
Fe2O30.01
K2O 0.01
MgO0.01
MnO0.001
Na2O0.01
NiO0.003
P2O50.01
SiO20.01
TiO20.01
V2O50.003
LOI0.01

Samples are dried at 105°C prior to LOI or fusion as laterites can easily absorb water from air. To minimize the matrix effects of the samples, the heavy absorber fusion technique of Norrish and Hutton (1969, Geochim. Cosmochim. Acta, volume 33, pp. 431-453) is used for major element (oxide) analysis. Prior to fusion, the loss on ignition (LOI), which includes H2O+, CO2 , S and other volatiles, can be determined from the weight loss after roasting the sample at 1000°C for 2 hours. The fusion disk is made by mixing a 0.75 g or 0.19g equivalent of the roasted sample with 9.75g of a combination of lithium metaborate and lithium tetraborate with lithium bromide as a releasing agent. Samples are fused in Pt crucibles using an automated crucible fluxer and automatically poured into Pt molds for casting. Samples are analyzed on a Panalytical Axios Advanced or Axios Max wavelength dispersive XRF.

The intensities are then measured and the concentrations are calculated against the Ausmon standard which adjusts the calibration. Control standards are run to verify the procedure. Matrix corrections were done by using the oxide alpha – influence coefficients provided also by K. Norrish. In general, the limit of detection is about 0.01 wt% for most of the elements.

Oxides and Detection Limits (%)

OxideDetection
Al2O30.01
CaO0.01
Co3O40.01
Cr2O30.01
CuO0.005
Fe2O30.01
K2O 0.01
MgO0.01
MnO0.001
Na2O0.01
NiO0.003
P2O50.01
SiO20.01
TiO20.01
V2O50.003
LOI0.01