Journal of Minerals & Materials Characterization & Engineering, Vol. 8, No. 9, pp 745-753, 2009 Printed in the USA. All rights reserved
Högbomite Associated with Vanadium bearing Titaniferous Magnetite of
Mafic-Ultramafic Suite of Moulabhanj Igneous Complex, Orissa, India
D. Beura1*, D. Acharya2, P. Singh1 and S. Acharya3
1 Department of Geology, Utkal University, Bhubaneswar
2Stewart Science College, Cuttack
3 155, V.I.P. Colony, Nayapalli, Bhubaneswar
* Corresponding Author:
Högbomite associated with vanadium bearing titaniferous magnetite has been identified in
mafic-ultramafic suite of rocks of Moulabhanj, Orissa, India. The igneous complex intruded into
granulite terrain of Eastern Ghat Super Group. The iron mineral assemblages are Ti-V
magnetite, martite and ilmenite. Högbomite occurs in association with Ti-V magnetite and
exhibits both primary and secondary micro-textures. EPMA study confirms the presence of
Key Words: Högbomite, Ti-V Magnetite, EPMA, Moulabhanj
Högbomite a complex oxide of Fe, Mg, Al and Ti is an important constituent of Fe-Ti-oxide of
igneous (basic-ultrabasic) complex of Moulabhanj area (200 56’N: 850 43’E) of Orissa, India.
The mineral was first reported by Gavelin [1] from Swedish Lapland and later in various places
in the world. In India, Devaraju et al., [2] reported högbomite in Fe-Ti oxide from Madangere of
Karnataka and Mohanty et al., [3-4] described from Boula-Nausahi igneous complex of Orissa.
Reports on this new locality suggests that högbomite may be more wide spread than in general
Presently studied Ti-V magnetite ore bodies hosted in mafic-ultramafic suites have been invaded
into the granite gneisses and granulites near the border zone between Iron Ore Supergroup
746 D. Beura, D. Acharya, P. Singh and S. Acharya Vol.8, No.9
(IOSG) and Eastern Ghat Supergroup (EGSG) at Moulabhanj (200 56’N: 850 43’E), Dhenkanal
district, Orissa, India [5]. The two Supergroups exhibiting contrasting characters in terms of
lithology, structure and grade of meta morphis m are separated by migmatite and mafic granulites
and are separated by Sukinda thrust zone (STZ) running east west. Moulabhanj igneous complex
crop out within EGSG in the south of STZ and the well-known Sukinda valley chromite field is
lying in the north. The co mplex hosted chromite, magnetite and högbomite. The ore microscopic
study was carried out at Department of Geology, Utkal University whereas EPMA studies were
done at IIT- Roorkee, Roorkee.
The present study area around Moulabhanj (200 56’N: 850 43’E) is lying within Easternghats
constituting southern part of the contact zone (STZ) between IOSG and EGSG. Ore bearing
mafic and ultramafic complexes have intruded into metamorphites of Easternghats belongs to
Proterozoic. The litho-types of the area comprises of charnockite, khondalite, migmatitic gneiss,
quartzo-feldspathic gneiss and pyroxene granulite, which are invaded by pegmatite and dolerite
dyke (Fig. 1).
Fig. 1. Geological map of Moulabhanj, Orissa.
Vol.8, No.9 Högbomite Associated with Vanadium bearing Titaniferous Magnetite 747
The mafic-ultramafic complexes of the study area are represented by peridotite, pyroxenite,
gabbro and their alteration products. It hosts chromite and V-Ti- magnetite. The other minerals
present are ilmenite, martite, spinel, hematite, goethite and chlorite. The lithosomes reveal green-
schist facies assemblages in contrast to the high-grade metamorphism of the rocks of EGSG into
which they have in truded. Magnetite is intimate in association with gabbro suite of rocks, which
is exposed as discordant bodies in the region.
In fact, the chromite and Ti-V-magnetite bearing ultramafic -mafic suites emplaced across the
contact zone are less deformed and metamorphosed. Thus, they are assumed to be invaded into
the zone under rifting only after granitic activity, metamorphism and fold movements.
Petrographic study of titaniferous magnetite was carried out by ore microscopic analysis (Leica
labour lux 12 pol. and Leica DM 2500 P). Various minerals identified are magnetite, martite,
ilmenite, spinel, högbomite and chlorite. (Fig.2 and Fig.3). Högbomite occurs as fine- to
medium-grained euhedral to subhedral crystals enclosed within or along grain boundaries of
magnetite and ilmenite and associated with spinel and chlorite. It is commonly granular in habit
with tabular, prismatic and slender shape. It is also found intergrown and included with other
minerals and often shows twinning may be repeated type.
Högbomite is opaque mineral but transparent in thin fragments. It is dark in colour and brown in
transmitted light. It exhibits pinkish grey colour, feeble pleochroism, lower reflectivity (<10%),
anisotropism and reddish brown internal reflection under reflected light (Fig. 2 and Fig. 3).
Studies indicate wide spectrum of crystal habits of högbomite. Idiomorphic grains exhibit
rhombohedral, bipyramidal and hexagonal habit (Fig. 2. A, B, C and D). Subhedral grains of
prismatic and platy högbo mite are present within magnetite (Fig.3.A) and interfaces of magnetite
and ilmenite (Fig. 2.D).
Small blebs and drops of högbomite within magnetite and ilmenite demonstrate the exsolution
phase/texture (Fig. 3.C). Exsolved ilmenite in magnetite and exsolved hematite in ilmenite is the
common textural pattern also traced in slides (Fig. 2.C and Fig. 3.B & C). Unmixing of solid
solutions of these minerals occurred during the post magmatic stage.
Högbomite in forms of small grains that occur along the margins of magnetite appears either to
replace magnetite or to overgrow on it. In cases, larger grains of högbomite replace magnetite
and overgrown on it to emerge magnetite as inclusion that may be considered as part of
replacement process (Fig. 2.A). Two generations of högbomite exist having been separated by
magnetite. The earlier phase of subhedral högbomite in magnetite has been replaced by
748 D. Beura, D. Acharya, P. Singh and S. Acharya Vol.8, No.9
subsequent phase of anhedral högbomite leaving vestige magnetite as a ring (Fig. 3.D). Incipient
growth of högbomite along the boarder of magnetite grain on the backdrop of martitised
magnetite indicates gradual replacement of magnetite (Fig. 3.F).
Most of the högbomite grains are rimmed by dark coloured chlorite of varying thickness.
Presence of chlorite along the grain boundaries of högbomite indicates the alteration of the later
from the earlier (Fig. 2.A, B and Fig. 3.A, F). Often högbomite shows replacement texture in
which overgrowth spinel and magnetite are replaced by it (Fig. 3.F). Twining habit of hexagonal
högbomite exist may be due to growth phenomena rather than pressure (Fig. 2.D).
Fig. 2. Photomicrograph of (A) Well-developed hexagonal högbomite (Hg) crystal with
magnetite (Mg) inclusion rimmed by dark coloured chlorite (Cl). (B) Bipyramidal crystal of
högbomite (Hg) in magnetite. Magnetite is partly altered to martite (Mt). (C) Rhombohedral
grains of högbomite (Hg) enclosed in martitised magnetite. The exsolved ilmenite is cut by
ilmenite plate, which in turn replaced by högbomite. (D) Hexagonal twin-crystals of högbomite
(Hg) exist in the interface of ilmenite (IL) and magnetite.
The Ti-V-magnetite exhibits polycrystalline granular texture the grain boundaries show triple
point junction (Fig. 3.D). It consistently demonstrates ex-solution lamellae/stringers of ilmenite
and partial martitisation along grain boundaries and cleavage planes. Hematite containing
Vol.8, No.9 Högbomite Associated with Vanadium bearing Titaniferous Magnetite 749
ilmenite exsolution lamellae is more abundant than independent (primary) ilmenite. Minor
secondary chlorite is ubiquitous.
Fig.3. Photomicrograph of (A) Subhedral platy and prismatic crystals högbomite (Hg) within
magnetite. (B) Högbomite (Hg) of subhedral habit occurs within ilmenite. Note that ilmenite
shows exsolution lamellae of hematite. (C) Belbs and drops of högbomite grains lying within
and along the boundary of ilmenite shows exsolution texture. Exsolution lamellae of hematite are
seen in ilmenite (D) Earlier subhedral grain of högbomite (Hg) in magnetite is replaced by later
anhedral högbomite (Hg) leaving vestige magnetite as a ring. Note that magnetite grains shows
750 D. Beura, D. Acharya, P. Singh and S. Acharya Vol.8, No.9
triple point junction (O) with interfacial angle of 1200 (E) Högbomite grains are oriented parallel
to the exsolved ilmenite lamellae/lath by replacing it. It indicates högbomite (Hg) is formed latter
to the ilmenite. (F) Högbo mite grains along with dark coloured chlorite grains replace martitised
magnetite forming ring around Magnetite showing widmansttaten texture.
Mineralogical identification of Ti-V magnetite was carried out by ore microscopic analysis that
indicates presence of magnetite, martite, ilmenite and högbomite in them. The presence of
högbomite is confirmed by EPMA (JEOL JXA-8600 M, SPI standards with an accelerating
voltage of 15 KV).
Högbomite is a rare mineral whose chemical formula is RII1.0-1.6Ti0.2-0.4RIII3.7-4.3O8 (where RII =
Fe, Zn, Mg; RIII = Fe, Al) [6]. The results of selected four spots examined by Electron Probe
Microanalysis (EPMA) are tabulated. The element compositions obtained are given in Table 1.
The Ti-V magnetite exhibits granular texture. Magnetite contains TiO2, Al2O3, MnO, MgO,
V2O3 and ZnO (Table 2). Ilmenite contains TiO2, Al2O3, Cr2O3, MnO, MgO and V2O3 (Table 3).
Table 1. Chemical analysis of Moulabhanj högbomite.
Sample No
. 56/10 56/14 58/3 58/9
26.86 27.91 25.9 28.49
TiO2 4.36 4.34 4.38 4.26
MgO 9.31 8.42 9.62 8.23
Al2O3 56.28 56.22 57.73 56.19
MnO 0.15 0.15 0.13 0.06
Cr2O3 0.05 0.04 00 0.05
ZnO 1.61 1.51 1.99 1.48
SiO2 0.00 0.32 00 0.01
V2O3 0.03 0.02 0.02 0.01
Total 98.65 98.92 99.77 98.78
Vol.8, No.9 Högbomite Associated with Vanadium bearing Titaniferous Magnetite 751
Table 2. EPMA of Magnetite grains.
Sample No
. 56/1 56/6 56/9 58/1 58/4 58/10
87.100 85.577 86.176 90.047 89.649 90.685
TiO2 2.775 2.330 1.838 2.287 1.162 1.1712
MgO 0.271 0.913 0.330 0.0542 0.170 0.138
Al2O3 0.949 5.424 1.880 1.377 1.043 1.371
MnO 0.113 0.061 0.030 0.048 0.165 0.022
Cr2O3 0.079 0.027 0.048 0.122 0.000 0.000
ZnO 0.104 0.000 0.000 0.000 0.051 0.000
SiO2 0.000 0.000 0.000 0.000 0.000 0.000
V2O3 0.015 0.012 0.013 0.011 0.011 0.011
Total 91.407 94.344 90.314 94.436 92.701 93.939
Table 3. EPMA of ilmenite grains.
Sample No
. 56/2 56/4 56/11 58/2 58/8 58/10
45.87 46.27 45.14 45.66 47.48 44.11
TiO2 51.73 52.06 52.20 52.79 51.54 53.31
MgO 1.30 1.112 1.13 1.29 1.42 1.27
Al2O3 0.00 0.00 0.03 0.05 0.10 0.09
MnO 0.57 0.84 0.70 0.65 0.60 0.80
Cr2O3 .081 0.04 0.12 0.01 0.00 0.04
ZnO 0.00 0.10 0.04 0.07 0.00 0.04
SiO2 0.00 0.00 0.00 0.00 0.00 0.00
V2O3 0.27 0.27 0.28 0.27 0.267 0.28
Total 99.83 100.73 99.66 100.76 100.45 99.99
The matrix högbomite is presumed to have formed from magnetite but there is no obvious source
of Al, alternatively the present magnetite-högbomite-ilmenite aggregates could have resulted
from recrystallization and oxidation of a pre-existing Fe-Mg-Ti-Mn phase (+ilmenite). In the
different composition, the matrix högbomite must have formed from a different mix of oxide
phases. Thereby implying compositional factors, including oxygen fugacity, rather than pressur e
and temperature, are main controls of högbomite chemistry.
The average analysis of samples is given in Table 1. It is richer in Al and impoverished in Ti.
Higher FeO and ZnO, nearly lacks Cr2O3 and MnO. Compared to the högbomite fro m Karnataka
752 D. Beura, D. Acharya, P. Singh and S. Acharya Vol.8, No.9
[2] and Baula-Nausahi, Orissa [4], these are richer in MgO, Zn and poor in Ti, Mn, Cr. Ti-poor
högbomites have also been reported [7, 8]. Zn is commonly present in appreciable amounts (1.48
– 1.99 wt% ZnO).
There is reciprocal relationship between Fe and Mg, Fe and Ti and Fe and Al indicate that Ti,
Mg and Al replace Fe in the högbomite structure. Low concentration of Mg in the mineral
derived from the magma having very-low MgO content [7-9]. Chemically the högbomite is
characterized by (i) narrow variation in alumina and titania values, (ii) consistently high Zn
values, (iii) moder ate Mn, Cr and V values similar to the co- existing magnetite, (iv) substitution
of Mg and Zn by Ti results in the replacement of spinel by högbomite.
Högbomite of Moulabhanj area is traced in Ti-V-magnetite; spinel and chlorite association,
which suggests that it is a part of the magmatic phenomenon. The magmatic derivation is
evidenced by absence of metamorphism. Morphologically it can be grouped into primary –
crystallized from the magma as exsolution and secondary- developed after spinel through
Högbomite exists as coarse grain and its randomly orientation in interstices of the ore minerals
suggest an early-crystallized pyrogenic phase. Thin scales/rods and small blebs of högbomite
occurring within magnetite represent the exsolved phase; the exsolution of högbomite
component may be due to falling temperature of crystallization [2]. Small patches within the
magnetite possibly demonstrate exsolution phase of högbomite. The slender scales and shreds of
högbomite rimming the spinel grains bear evidence of formation at the expense of spinel [10,
11]. According to Jayaraj et al., [9] the early-formed spinel crystals reacted partially with the
magma resulting in högbomite rims.
According to Grew et al., [8] högbomite occurs in association with spinel and chlorite points to
the secondary nature of högbomite. The högbomite associated with spinel is formed by the
substitution of Ti2+ for (Mg2+, Fe2+) and Fe2+ for Al3+ under silica under-saturation and high
oxygen fugacity condition [4].
In a thermodynamic treatment of the stability of högbomite, Petersen et al., [12] proposed a
number of högbomite-forming reactions that included the breakdown of magnetite and spinel.
Substitution of Mg and Zn by Ti according to Friedman [10] is the mechanism of högbomite
formation. Zakrzewski [11] suggested that the loss of Al in högbomite is compensated by
oxidation of magnetite as usually högbomite is noted along margin of magnetite.Relationships of
högbomite with ilmenite, magnetite and chlorite show that its crystallization took place after
formation of the ore minerals but before or simultaneously with chlorite.
Vol.8, No.9 Högbomite Associated with Vanadium bearing Titaniferous Magnetite 753
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[8] Grew, E. S., Hiroi, Y. and Shiraishi, K., 1990, “Högbomite from the Prince Olav Coast, East
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[9] Jayaraj, K.R., Khanadali, S.D., Devaraju, T.C. and Spiering, B., 1995, “A study of högbomite
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[10] Friedman, G.M., 1952, “Study of högbomite.” Am. Minerl, Vol. 37, pp.600-608.
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Min. Mh. H-8, pp.273 - 280.
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