a copy to be downloaded by an individual for the purpose of research and
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STUDIES OF TUNGSTEN
ii. thesis
presented in partial fulf ilraent of the requirements for the decree of l•Ias-ter of Science in Chemistry
at
Hassey University
BERTRAU FRANCIS QUIN
1972
11Knowinc; is not enouch
We nust ai:)ply
Wi llin3 is not enough We must, dott
Goethe
ABSTRJ\CT
Sect ion I: Stu~ies were carried out t o deternine the optimum conditions for the determinat ion of t unc-sten with a large quart z emission spectrograph. By naking use of silver chloride as a carrier, large electrodes and the 2947 A analysis l ine, soils and rocks containine as low as 10 ppm tungsten could be analysed with reasonable reproducibility. Reliable results were not achieved for plant samples however, and the productivity of t he method was very low.
In view of these shortcomings, the use of the dithiol colorimetric reagent for the analysis of tungsten was investigated, and a reliable procedure with a
detection limit of O .1 ppra and very high productivity was developed for the analysis of soils, rocks and vee;etation.
Section II: Pot trials were carried out to investigate the uptake of tungsten by young plants of Nothofagus menziesii (silver beech). It was found that, although most of the tungsten taken up froo the soil remained in the roots, the concentrations of this element in the
leaves, steras and roots of the plants were all related t o the tungsten concentration in the soil.
Section III: Biogeochenical and geochemical investigations were carried out in an area of tungsten mineralisat ion at Barrytown, Westland. The results of preliminary invest i- gations showed that the levels of manganese, tin and lead in the soil were associated with t he tungsten level, and may therefore be of possible use as pathfinders for t ungsten.
An investigation was carried out t o determine whether the concentration of tunGsten in plants could be used t o predict the concent rat ions of this element in the soil. It was found that while shallow-rooting species such as tree-ferns could be successfully used to detect soil anomalies, the relationship between the levels of
tungsten in soils and tree species was rather less distinct. Detailed study of trunk and soil samples indicated that this was caused lareely by variation in soil properties, particularly pH, which was found to affect the solubility of tungsten.
Despite the unsuitability of trees for indicating concentrations of tungsten in t he soil, i t was found that tree-trunk analysis could be successfully used to locate tungsten-bearinG veins, without restriction in the
number and types of species used.
TABLE OF CONTENTS
ABSTRACT
TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES
GENERAL INTRODUCTION
SECTION I - DEVELOPHENT OF ANALYTICAL HETHODS A. INTRODUCTION
B. EMISSION SPECTROGRAPHY
1. Review of existing procedures 2. Apparatus
3, Preparation of standards 4, Preparation of samples
(a) Rock and ore samples
(b) Soil and stream-sediment samples (c) Plant samples
5, Improvement of det ection limit (a) Investigation of analysis line (b) Investigat ion of elect rode size {c) Investigation of silver chloride as
page (iii) (v) (ix) (x)
1 7 8 10 10 10 11 11 11 11 11 12 12
14
a carrier
14
6. Investigation of palladium as an internal
standard 16
7, Reproducibility and precision tests 18
8 .
Final spectrographic operating conditions 209, Conclu.si oa 20
C. COLORIJ1iE TRY
1. Review of existing procedur es 2. Development of the method
(a) Preliminary treatment (b) Ashing of vegetation
(c) Decomposit ion of geochemical samples (d) Extraction of water-soluble tungsten
in soils
(e) Parameters affecting the formation and
22 22
25 25
26 26 29 extraction of the complex 31 (i) The nature of the dithiol solvent 31 (ii) Length and temperature of heating 33 (iii) Acidity of sample solution 35 (f ) Elimination of interferences 363, Experimental 38
4, Reagents 39
5, Procedures 39
(a) Determination of tungsten in vegetation 39 (b) Determination of total tungsten in
soils, stream-sediments and rocks 40 (c) Determination of water-soluble tungsten
in soils 41
6. Testing of method
(a) Reproducibility test s (b) Recovery test s
(c) Sensitivity (d) Prod~ctivity
7 .
ConclusionSECTION II - THE UPTAKE OF TUNGSTEN BY NOTHOFAGUS t.IENZIESII
A. INTRODUCTION B. INVESTIGATION
1. Materials and methods
(a) Sett ing-up of experiment
(b) Chemical form of added tungsten 2. Result s and discussion
C. CONCLUSIONS
SECTION III - GEOCHEMICAL /\.ND BIOGEOCHEMICAL STUDIES OF TUNGSTEN AT BARRYTOWN
A. PRELIM:INAR.Y INVESTIGATION 1. Introduct ion
2. Sampling methods (a) Sampling sites (b) Species sampled
(c) Plant organs sampled 3. Analytical methods
(a) Soils
( i)
(ii) (iii) (b) Plants
Tungsten
Molybdenum and tin Other metals
( i) Tungsten (ii) Other metals ( c), General
4 .
St at istical treatment of data (a) Cumulative fpequency plots (b) Correlation coefficients5 .
Result s and discussion (a) Analytical data(i) Soils (ii) Tree dat a
General Tungsten
(i i i) Tree-fern data General
Tungsten
(b) Cumulative frequency plots (i) Tungsten
(ii) Manganese (iii) Lead
(iv) Tin ( v) Iron
(vi) Molybdenum (vii) Zinc
(viii)Copper and Nickel
42 42 42 42 44 44
45 45 49 49 49 51 51 58
60 61 61 63 63 63 65 66 66 66 66 66 67 67 67 67 68 68 68 70 70 70 72 72 74
75 75
75
75
75
77
77
77
78 78 78 785 • (c) Correlation coefficients
(i ) Inter-soil correlations Stream-bank soils
Ride;e soi ls Discussion
(ii) Plant-soil correlations St reau-bank tree-ferns Ridc;c troes
Discussion (d) Conclusioc..s
79 79 79 80 80 82 82 32 82 84
B. FURTHER INVES'I'IGA7IOrJS 8 6
1. Introduction 86
2. Investi[;ation of poor tree-soil correlations 87
3.
(a) Variation of tungsten with distance into
(i) (ii)
t runk Sai::plinc
Results and discussion
(b) Variation in concentration of tuncsten
87
f3 7 87
in trunk and surrounding soil 87
(i) Description of site
87
(ii) Sampling 89
(i i i) Results and discussion 89 (c) Effect of tree a~e on concentration of
tu.ngsten in outer t runk 91
(i) Sai:qling 91
(i i) Result s a11d discussion 91 (d) Differences in soil pro~ertics between
sit es 93
(i) Introduction 93
(ii) Tucc sten concentration in various
size fractions 93
(iii) /i.r.10t....nt of ·tungsten in the various
size fractions 96
(iv) 1'later-soluble tungsten in the
various Eize fractions 96
( v) 1)i'.I of t l1c various size fractions 9'7 ( vi) Orcanic content of ·the various
sizo fractions 97
(e) Water-soluble tungsten and pH 98
(f) The effect of distance from source on the distribution of tungsten between
coarse and fine soil fractions 98
(g) Distribution of tungsten between magnetic and nonnaBnetic soil fractions
(h) Variation in percentage water-soluble tungsten with distance from source (i) Discussion and conclusions
The use of trunk sampling in locatine;
tungsten-bearinCT veins (a) Introduction
(b) Description of areas
(i) Area containing transported tungsten (ii) Arca containing tungsten-bearing
veins (iii) Sampling
99 100 100 103 103 103 103 104 104
3. (c) Results and discussion ( i ) Trunl~ concei-:i-crations
(i i) Diatribu~ion of tunesten in trunk (i i i)Soil versus trunk analyses
(d) ~ransect across veins
(i ) Introduction
(ii) Sa~pling and analys is (i i i)Results and discussion (e) Conclusions
Slfi.].fAl\.Y AND GEHER/\.L C JECLUSIONS
APPElIDICES
1. Fresh, dry, ar.d ash weic:Yc data f or pot t r ial plant.s
2. Individual plant da-'ca fo,.-. ti1unk-sanpline;
-c,ransect AUTHOR IlTDEX
REFE2.E1TCES
PUBLICATIONS 1mISI!TG PROE THIS '.;:'I-mSIS l\.CKH O'WLEDGEI iE:i-TT S
104 104 105 105 105 105 107 107 108 109
113 114 115 118 124 125
Fig. 0. I
Fig. I.1 Fig. I.2 Fig. I. 3
Fig. I.~- Fig. I.5
Fie;. I. 6
Fie. I. 7
Fig. I.8
Fi[;. II. 1
Fie;. II. 2
Fig . III.O Plate III.1 Fie. III.1 Fi~. III. 2 Fie. III.3 Fir;. III. 4 Fig. III. 5
Fig. III. 6
Fie. III. 7
Fig. III.8
Fig. III.9
LIST Or FIGU?~ES
1iap showinc; geoloey of Paparoa TI.ange. After Bowen (1964-) .
Volatilisation curves for tungsten Emission spectrocraph workinG curves
for (h) soil/rock and (B) plant ash Effect of potassiw~ hydrogen sulphate
on tun~sten analysis.
Ext raction of water-soluble tungsten vs tine.
/\.bsorbance vs time from (a) 10 J.J..G of tungsten; (b) blank, with old dithiol solution .
Effect of acid concentration on the extraction of tu~gsten (a) in the presence of 10% tin (II) chlor ide;
(b) in t~e absence of tin(II) chloride. Effect of tin (II) chloride
concentration on the absorbance from ( a ) 1 0 /. ~ g t ung st en ; ( b ) 1 0 0 q g
molybdenw:1.
Calibration curves for -the colorir:i.etric determination of tungsten (a) in soils, st ream sediments and rocks; (b) in vec;e·cation.
~unc;st e~ concentration in the plant organs as a function of the
concentration of tungsten in the soil.
Percent age uptake of tungsten as a function of root weigh~.
I-.iai) showing Barrytow!1 st;udy area Leaves fror.1 ·che t rees sa1:1pled.
Conparison of tungsten analyses by
e1:1ission spectroGraphy and colorinetry Cur:mlativc frequency plots for soil
da-ca
Variation of tungsten in streao-bank soils with mane;anese, lead and t i:i.1. Vari at ion of tungs-c,en in ridge soils
with manganese, lead and tin
Variation of tungsten in stream-bank soils with tuncsten in tree-ferns
(a) data plot; (b) profiles.
Variation of tungsten in ridge soils with tunGsten in Quintinia acutifolia twigs and I-1yrsine salicina leaves
(a) data plots; (b) profiles.
Distribution of tungsten between 10-40 and -100 mesh fractions as a function of distance from source.
Variation of total and water-soluble tunGsten in stream-bank soils with tunesten in tree ferns .
Transect across tungsten-bearing veins.
After page no.
5
1616 28 29 34
35
38
42
52
55
6264
66
75 79 81
100
102 108
LIST OF TABLES
page
Table I.1 Tungsten analysis lines 13
Table I.2 Reproducibility and recovery tests 19 Table I.3 Spectrographic operating conditions 21 Table I.4 Comparison of results from different
methods of decomposition 30 Table I.5 Comparison of absorbances from 10t.,g
tungsten using different dithiol
solutions 32
Table I.6 Analytical data for replicate
determination of tungsten in plant,
soil and rock samples 43
Table I.7 Recovery of added tungsten frorn soil
and plant ash 43
Table II.1 Data for tungsten in soil 50 Table II.2 Data for tungsten concentrations in
plant organs
52
Table II.3 Data for copper and zinc concentrations
:in plant organs 54
Table II.4 Data for 'i:;ungsten uptake 56 Table II. 5 Data for percentage distribution of
tungsten 57
Table III.1 Analysis condit ions for atomic
absorpt ion spectrophotometry 69 Table III.2 Results for replicate atomic absorption
analysis of a tree-fern sample 69 Table III.3 i\.nalytical data for soils 71 Table III.4 Analytical data for trees 73 Table III. 5 Analytical data for tree-fern leaves 76 Table III.6 Correlation result s for soil data 80 '.i'able III.7 Correlation results for tungsten in
in plants and soils 83
Table III.8 Variation in tungsten concentration
with distance into trunk 88 Table III.9 Trunk and soil variability data 90 Table III .10 Variation of tungsten concentration in
trunk with species, age and size of
tree 92
Table III.11 Tunesten data for trunks and soils
frora Sites I and I I 94
Table III.12 Soi l size fraction data for Sites I
and II
95
Table III.13 Data for magnetic separation of soil
sample 101
Table III .14 Comparison of tree and soil tungsten d&ta for areas of (i) transported tungsten, and (ii) tungsten-bearing
quart z veins 106
Table III.15 Distribut ion of tungsten in trunks of two trees growing over tungsten-bearing
veins 106
INTRODUCTION
The term biogeochemistry_was first used in 1922 by the Russian scientist Vernadsky, who defined it broadly as the study of the relationships between life, in all its forms, and the geological environment. Biogeochemical prospecting is the application of this concept to prospecting for minerals, by the chemical analysis of plant_ samples collected from
suspected areas of mineralisation, and is based on the general presumption that an an~alous concentration of a metal in the substrate, hopefully caused by the presence of a valuable ore body, will result in an anomalous concentration of that element in the vegetation growing thereon.
The first recorded use of biogeochemical prospecting was
in
1936, when trial plant surveys carried out byPalmquist and Brundin of the Swedish Prospecting Company indicated the presence of abnormally high contents of tin and tungsten in Cornwall; and lead and zinc in Wales, in the leaves of trees and shrubs growing in soils containing large amounts of these metals. Unfortunately, apart from a patent covering the technique used (Brundin, 1939) very little of their work was published.
In the years following this early work, there has been a great deal of biogeochemical research carried out, particularly in Russia, where understanding of the factors affecting the success of biogeochemical prospecting has
progressed to the stage where all prospecting teams now have at least one biogeochemist included.
Unfortunately, the same is not generally true of Western countries, largely due to a lack of close liaison between mining companies and university research groups.
Much excellent biogeochemical research has failed to be
applied to prospecting because of a lack of appreciation of, or interest in, the practical requirements of a prospecting method on the part of the scientist. On the other hand, many mining companies, for example in Australia, have tried biogeochemical prospecting for themselves, but because of insufficient study of the factors which can affect the success of the method, obtained poor results and rejected this type of mineral exploration~ If biogeochemical
prospecting is to develop further, this situation must be rectified.
In New Zealand, most biogeochemical prospecting research has been based on the asswnption that the soi 1 indicates what is in the bedrock, and arg~es that if plant analysis can be used to indicc.t e what is in the soil, then plant sampling is to be preferred to soil sampling, because the samples are lighter and collection is faster, particularly in areas where the presence of thick layers of forest litter, humus - rich soil and t ree root s render soil sampling
extremely slow (Brooks and Lyon,
1966).
However time has proven that these advantages do not sufficiently outweigh the disadvantages such as the necessity for skilled samplers and the fact that, in many cases, before the concentration of a metal in the soil can be even approximately predicted from its concentration in the plant, several factors such as the soil pH and drainage must be taken into account. Althoughcomputerised mathematical techniques incorporating these factors, for example multiple regression analysis, can be used to improve the prediction of soil anomalies from plant data (Timperley, Brooks and Pet ersen,
1971),
this putsbiqgeochemical prospecting out of the.reach of small companies, requires s t i l l more skilled personnel, and severely reduces its speed advantages.
It seems, therefore, that i f biogeochemical prospecti~g is to be considered by Australasian mining companies as a
worthwhile tool in the search for minerals, it must be demonst~ated that in certain geological, topographical and climatic environments, i t can give more information than soil
sampling. For example, the presence of deep soil or an unmineralised overburden, or the effect of leaching or soil creep, can all prevent the presence of mineralisation from being manifested in the upper soil ( from where soil samples are taken), or may produce a soil anomaly at some distance from the actual source. The extensive root systems of some tree species can reach and therefore "sample" deep soil and even bedrock thus pinpointing the exact position of ore bodies.
Some work of this nature has been carried <;>ut in North America, and recently in Australia (Severne,
1972).
For example, Keith
(1968)
by analysing the covering vegetation in the upper Mississippi valley district, successfully detected lead and zinc miner~lisation under an overl;)urden of loess \there no. soil anomalies were obvious.However, where loess was absent, he found that a oil analysis gave better results than plant analysis. Another example is provided by the work of Kleinhampl and Koteff (
1966)
who found that conifer samples indicated -µraniwn deposits at depths as great as '/0 feet. There is, however, very little published work dealing with the success of plant sampling in areas where, beca~se of factors such as high rainfall and rugged topography, leaching, soil creep and landsliding obscure the soil-bedrock relationship.The application of biogeochenical prospecting has also been hindered by the lack of suitable rapid methods of
analysis for some metals. This has been particularly true for tungsten. Althoughprevi·ous workers have studied the tungsten content of plants in relation to biogeochemical prospecting (Pali;lquist and Brundin, I':npublisho.£17
Kovalevsky
1966),
the success of their investigations were severely limited by their method of analysis, naoely the emission spectiograph. This instrument, oesides beingrelatively slow in operation, is somewhat imprecise and nas a poor limit of detection for tungsten, particularly in samples of high alkali-metal content such as plant ash (Hi tche 11,
1964).
Although the faster and more sensitive colorimetric methods for the deternination of tungsten in soils and rocks, using either thiocyanate or toluene - . 3, 4 - dithiol ( di thiol) have been in use for some years (Ward,
1951;
North,1956),
they had not been successfully applied to the analysis of vegetat-: ~ . ..,_. The thiocyanate method of Aull and Kinard
(1940)
was too insen~itive for the determination of natural tungsten in vegetation, and the dithiol method of Allen and Hamilton
(1952)
was too slow and insensitive to be suitable for\
'
biogeochemical prospecting. There therefore existed a real need for a rapid, sensitive, and reproducible method for the determination of tungsten in vegetation.
This need became apparent to me some months after the discovery in 1970 of tungst en at Barrytown,
Westland, by Carpentaria Exploration, when, with the
kind permission and extensive assistance of that company, I began an investigation into the feasibility of
biogeochemical prospecting for tungsten in the area.
The area involved in the st udy is shown in
Fig. 0.1, ind consist s of a granite mass of approximately a square mile in area, which rises from an altitude of approximat ely 100v at its western extremity to about 1500v in the east, and is surrounded to the north, south and east by hornsfels and greywacke, and to the west by recentQJ.rficial deposits. The tungsten mineralisation a, approximately 98-99% scheelite and 1-2% wolframite, exists in a series of quartz veins containing discreet crystals up to¼" size and as scheelite disseminated in griesen veins and veinlets up t o 2-3mm in thickness. The
dimensions of the quartz veins are generally obscured, but appear to have a strike length of 100-200' with a maximum vein size of 0.7m, and tend to occur in swarms containing 10-40 veins over a width of 2-3m.
The annual rainfall of the area is high, approximately 110", with maximum and minimum monthly averages of 14" and
4"
in October and December respectively, and the leachingresulting from this, in combination with the granite
parent rock, has produced a soil poor in nutrients and of low pH. The soil consists of a dark-brown humus-rich
A horizon approximately 0.3m in depth, and lighter brown B horizon of extremely variable thickness and lower organic content. Both horizons contain many rock fragments. The vegetation is predominantly' . ,tlothofagus Jeruncata (hard beech) and Weimannia racemosa (kamahi), with increasing
aDescription of mineralisation provided by Mr J. A. C. Painter, Party Leader, Hokitika, Carpentaria Exploration Co. Pty Ltd.
77 N
TASMAN SEA
76
75
74
73
u
Fig. 0.1. Map showing geology of Paparoa Range.
After Bowen (1964).
KEY
contact ~
fault
---1'
concealed - - _ main road - - - -
LITHOLOGY
po~t MeSoLo;c
~awks Utlj brecc.ia.
;
.
~ c..oarsel:, <.~tQait1e-
• ~ <f.<4«r1L ,,or('Ao .. 'j
..
:ra.~,
fe. f'°'"'jl\eiss· wl~ "'°"j /e11f;L,lc..r
<.;,qrse ~'j"'"-t, fes .,.,.(oss:t,f<rous ;I\.
J.,..,-af~J.. Ja.rk-
<Jre'j )r<!'.{OA.10.c.lce.
" L """; qe,e" t.«te,(
1 fd"• t"e t•tm S I
L < a,k,.,.,lf;'fe J,_o -
-, J,or:fe
.,,,J
il,tJ<·i fe." >
dominance of ~othofagus menziesii (silver beech) at higher alt itudes, The pale-grey leached A
2 soil horizon, characteristic of the mor- producing beech species, was observed in many flatter areas. Chief secondary species include Quintinia acut i folia and Myrsine salicina, and much of the forest floor is covered in a dense growth of
ferns such as the ubiquit ous Blechnum discolor (crown fern).
The tree fe!'nS Cyathea medullaris (king fern) and
Dicksonia sguarrosa (wheki) are common on stream banks, as wdre oany s~aller f6~ns such as the Blcchnum species.
To conclude this eeneral introduction, the aims of this project may be summarised broadly as follows:
1. To develop rapid, sensitive and reproducible procedures for the det ermination of tungsten in vegetation, soils and rocks, in any concent ration, on a routine basis,
2. To determine whether biogeochemical prospecting has any useful role to play in the detection and pinpointing of tungsten ore bodies, and to compare its success with that of soil sampling, particularly in areas subject to leaching, soil creep and landsliding,
3, To investigate some of the factors which obscure the plant -substrate relationship with respect to tungsten, to assist in the interpretation of future field work.
