Thai Geoscience Journal 2 (2), 2021, p. 61-71 61
Copyright© 2021 by the Department of Mineral Resources of Thailand
ISSN-2730-2695; DOI-10.14456/tgj. 2021.6
Geology, occurrence and gemmology of Khamti amber
from Sagaing region, Myanmar
Thet Tin Nyunt1*, Cho Cho2, Naing Bo Bo Kyaw3, Murali Krishnaswamy4,
Loke Hui Ying5, Tay Thye Sun5, Chutimun Chanmuang N6.
1 Department of Geological Survey and Mineral Exploration, Ministry of Natural Resources and Environmental
Conservation, 15011 Nay Pyi Taw, Myanmar
2 School of Earth Sciences, China University of Geosciences (Wuhan); Myanma Gems Enterprise, 15011
Nay Pyi Taw, Myanmar
3 Myanma Gems Enterprise, 15011 Nay Pyi Taw, Myanmar
4 Department of Chemistry, NUS High School of Mathematics and Science, 20 Clementi Ave. 1, Singapore 129957
5 Far East Gemological Laboratory, 12 Arumugam Road# 04-02, LTC Building B, Singapore 409958
6 Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090, Vienna, Austria
* Corresponding author: thettinnyunt@ gmail. com
Received 17 March 2021; Accepted 4 June 2021
Abstract
A large quantity of Burmite (or Myanmar amber) is produced at Tanai in the Hukaung valley in
Kachin State and at Hti Lin (Tilin) in the Magway Region. Another occurrence of amber is found
in Pat-tar bum (also called Pat-ta bum) which is located near the Nampilin stream, about 40 km
southeast of Khamti (Hkamti), Khamti Township, Sagaing Region. The present mining sites in
Pat-ta bum are Laychun (Lachun) Maw (most productive), Kyat Maw, Shan Maw, Gyar Maw,
Kyauk Tan Maw and Nameindra Maw. Low grade metamorphic rocks, Kanpetlet schists and
similar schists to the Naga Hills are exposed in the eastern part which include glaucophane schist,
graphite schist, and epidote schist. Sedimentary units of Miocene age of the Upper Pegu Group
are widely exposed in the western, middle and northeastern part. Amber is found in Orbitolina
(mid-Cretaceous) bearing limestone which ranges from a few centimetres to up to two metres in
thickness. This limestone is intercalated with sandstone and carbonaceous shaley limestone and
sometimes together with carbonaceous materials. The bedding dips vary from 20 to 35 and
amber production follows the bedding plane. Amber is also found in sandstone and carbonaceous
shale. The primary amber mining is carried out by blasting the amber-bearing limestone,
sandstone and carbonaceous shaley limestone along their bedding planes and aditing. The colour
of Pat-tar bum (Khamti) amber varies from yellow, greenish-yellow, orangy-yellow, golden
yellow, brownish-yellow and brown. Gemmologically, it is transparent to opaque and the
refractive index ranges from 1.53 to 1.54 (spot reading), and the specific gravity ranges from 1.03
to 1.09. Ultraviolet radiation analyses show that very strong chalky yellowish-blue under long
wave and weak chalky yellowish-blue or greenish weak chalky yellowish-blue or greenish under
short wave. Some of the deep brownish material displays weak chalky blue or yellow under long
wave ultraviolet light and inert under short wave ultraviolet light. Inclusions that identified in
amber samples in the present study are flattened gas bubbles, flow marks, some brownish organic
debris and various organic inclusions (spiders, flies, feather-like and plant-like inclusions and
other organic materials). Eleven analysed specimens of Pat-tar bum amber were quite similar to
one another and the IR features are dominated by a group of absorption bands at around 2800–
3000 cm–1, relatively narrow bands in the range of 950–1750 cm–1 overlaying a broad hump at
800–1400 cm–1, and a weak broad band at around 3420 cm–1. Pat-tar bum amber does not show
the characteristic IR and Raman bands of young copal (which lie in the 1050–1250 cm–1 region
and at 1764 cm–1), which provides the confirmation for the older age of the amber ie, mid-
-Cretaceous as confirmed by Orbitolina sp. in the host limestone.
Keywords: amber, FTIR and Raman spectra, Khamti, Orbitolina sp., Pat-tar bum
62 Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71
1. Introduction
Major production of Burmite (Myanmar
amber) in Myanmar is from Tanai, Hukaung
valley in Kachin State and Hti Lin (Tilin),
Magway Region. Another occurrence of amber
is found in Pat-tar bum (also called Pat-ta bum)
which is located near the Nampilin stream,
about 40 km southeast of Khamti (Hkamti),
Khamti Township, Sagaing Region and about
112 km southwest of Tanai (Fig. 1). The
present mining sites in Pat-tar bum are
Laychun (also spelled Lachun or Lachon) Maw
(most productive), Kyat Maw, Shan Maw,
Gyar Maw, Kyauk Tan Maw and Nameindra
Maw (“Maw” means “mine” in Myanmar)
(Thet Tin Nyunt et al., 2019, 2020).
2. Geology
Paleocene to Eocene molasse-type sedimen-
tary units of the Paunggyi Formation and the
Cretaceous units are locally exposed including
limestone in the study area (Fig. 2). Ultramafic
and mafic intrusions of mostly Jurassic age also
occurred (Soe Thura Tun et al., 2014). These
intrusions include peridotite and serpentinite
which are the important source for jadeitite near
Nansibon (Cho Cho, 2016; Kyu Kyu Thin, 2016).
Low grade metamorphic rocks, Kanpetlet schists
and similar schists to those of the Naga Hills are
exposed in the eastern part which include
glaucophane schist, graphite schist, and epidote
schist. Orbitolina sp. bearing limestone (mid-
-Cretaceous, Albian?) intercalated with sandstone,
shaley limestone and carbonaceous limestones are
exposed in the Pat-tar bum area. Sedimentary
units of Upper Pegu Group of Miocene age are
widely exposed in the western, middle and
northeastern part.
3. Occurrence of Amber
Amber from Pat-tar bum is found in
Orbitolina sp.(mid-Cretaceous, Albian?) bearing
limestone (Fig. 3). The fossils that present in
the amber bearing limestone can only identify
that these fossils ranges from Lower Aptian to
Albian. So more thin sections are necessary for
further identification of this important fossils
(Tian Jiang, pers. comm.). The thickness of
amber bearing limestone is ranges from a few
centimetres to up to two metres. This lime-
stone are intercalated with sandstone and
carbonaceous shaley limestone and sometimes
together with carbonaceous materials (Thet Tin
Nyunt, et al., 2019, 2020).
Fig 1: Location map of the Pat-tar bum amber mine in Sagaing Region.
Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71 63
4. Amber Production
Five major production sites including 13
blocks where the mining operation has been
operated by Sea-Sun-Star Co. Ltd. are:
Laychun (Lachun) Maw, Kyat Maw, Shan
Maw, Gyar Maw and Kyauk Tan Maw (Fig. 4).
Nameindra Maw is now under suspension.
Among them, the Laychun Maw is currently
the most productive. The dips of the bedding
vary from 20 to 35 and amber production is
carried out along the bedding plane by adits.
The primary amber mining is carried out by
blasting the amber-bearing limestone, sand-
stone and carbonaceous shaley limestone along
their bedding plane and aditing into the
limestone. Excavated amber-bearing limestone
were sorted by manpower outside of the adit
(Figs. 5, 6 & 7).
5. Gemmology
The colour of Pat-tar bum (Khamti) amber
varies from yellow, greenish-yellow, orangy-
-yellow, golden yellow, brownish-yellow, brown
and reddish brown (Fig. 8). Clarity is from
transparent to opaque, the refractive index ranges
from 1.53 to 1.54 (spot reading), and specific
gravity (SG) ranges from 1.03 to 1.09. These
ranges are typical of amber (O’Donoghue, 2008)
where the higher SG is due to the attachment of
calcite matrix. Ultraviolet radiation analyses show
that very strong chalky yellowish-blue under long
wave and weak chalky yellowish-blue or greenish
Fig 2: Regional geological map of the Pat-tar bum area (after Soe Thura Tun et al., 2014).
Fig 3: Orbitolina sp. in amber bearing mid-Cretaceous (Albian?) limestone (10×, cross-polarised transmitted
light).(photos by Cho Cho)
1 mm
64 Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71
Fig 4: Location map of the Pat-tar bum amber mines.
Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71 65
weak chalky yellowish-blue or greenish under
short wave (Kocsis et al., 2020). Some of the deep
brownish material displays weak chalky blue or
yellow under long wave ultraviolet light and inert
under short wave ultraviolet light.
6. Inclusions in Amber
Inclusions that are contained in amber
samples collected the present study are flattened
gas bubbles, flow marks, some brownish organic
debris and various animal inclusions (spiders,
flies, feathers-like and plant-like inclusions, and
organic materials)(Figs. 9 & 10).
7. FTIR and Raman analyses
In the present study, eleven samples of Pat-
-tar bum amber were analyses by FTIR (Fourier-
-transform infrared) and Raman analyses. Fig. 11
presents a pair of infrared absorption [recorded in
ATR (attenuated total reflection) mode] and
Raman spectra obtained from amber sample KT21,
which is representative of all samples analysed
herein. The IR spectrum is dominated by a
group of absorption bands at around 2800-3000
cm–1, relatively narrow bands in the range 950-
1750 cm–1 overlaying a broad hump at 800-
1400 cm–1, and a weak broad band at around
3420 cm–1 (Fig. 11, top; for details see Thet Tin
Nyunt et al., 2020). The positions and relative
intensities of bands in the IR spectrum of
Khamti amber are similar to those seen in the IR
spectra of Myanmar amber from Tanai and Hti
Lin regions reported by various authors (eg
Tay et al., 2015; Liu, 2018; Chen et al., 2019;
Jiang et al., 2020; see Fig. 12), with the
exception of a broad band at around~ 3420 cm-1
(present study) or~ 3500 cm–1 (Thet Tin Nyunt
et. al., 2019), respectively, in the spectra of
Khamti amber. The absence of bands at 3048,
1642 and 887 cm–1 in the Raman spectrum
(Fig. 11, bottom) as well as in the IR spectrum
confirms that the Khamti material is amber and
(d)
(a)
(c)
(b)
Fig 5: Amber excavation at Laychun Maw:(a) Manual extraction of amber by manpower outside of the adit;
(b) amber with carbonaceous materials in limestone;(c) extracted amber and (d) yellowish brown honey
colour amber from Laychun Maw.(photos by Thet Tin Nyunt)
66 Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71
(a)(b)
(c)(d)
(a)(b)
Fig. 6: Nature of amber bearing limestone and amber production at Laychun Maw:(ab) Entrance for adit of
the amber bearing limestone along the bedding plane where the amber is obtained;(c) The amber from amber
bearing limestone is transported by a pulley system (yellow bucket with rope and pulley);(d) Intercalation of
amber bearing limestone and carbonaceous materials, sometimes with sandstone.(photos by Thet Tin Nyunt)
Fig. 7:(ab) Vertical shafts (1.2 m across, locally called Laybin) are also used to reach the amber bearing
limestone at Kyat Maw.(photos by Thet Tin Nyunt)
Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71 67
not copal (Brody et al., 2001; Wang et al., 2015;
compare also Liu, 2018).
8. Discussion and Conclusion
Gemmological properties of Khamti amber,
such as refractive index, specific gravity and
bright luminescence under LWUV illumination,
are quite similar to ambers from the Tanai and
Hti Lin regions. A difference consists in the
broad, OH stretching related IR absorption
band around 3500 cm-1 (3420 cm-1 in our samples)
in the spectra of Khamti amber. This band is not
found in amber from Tanai and Hti Lin, and it
can be attributed to OH stretching. In our
previous study (Tay et al., 2015), the analysis of
Tanai and Hti Lin amber was carried out with
only five samples each and the IR work was
focused at the range 3000 cm-1.
Thus, following the discovery of 3500 cm-1
absorption in Khamti amber, a preliminary
analysis of the Tanai and Hti Lin samples around
3500 cm-1 found that some samples appeared to
have a peak at 3500 cm-1 which we need to do
further analysis to confirm it. Therefore, consi-
dering the presence of carbonyl groups, this
hydroxyl can be assigned to carboxylic acid,
rather than molecular water in Khamti amber.
The characteristic FTIR and Raman spectra of
young copal have not been observed from the
Khamti amber which provides confirmation for
the older age of the amber ie, mid-Cretaceous
(Albian) or older age as confirmed by the
Orbitolina sp. in the host limestone. Moreover, it
appears likely that Khamti amber was captured
and buried earlier or during the formation of the
mid-Cretaceous (Albian) limestone.
Fig. 8:(a) Twenty one analysed samples of amber for this research range from 0.45 ct (small brownish piece
at the left) to 2.49 ct (yellow sample at the centre).(photo by Tay Thye Sun);(b) Khamti ambers with different
colour varieties.(photos by Thet Tin Nyunt)(scale bars are 10 cm in length).
68 Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71
Fig. 9: Inclusions in Khamti amber:(a) Fly;(b) Mosquitoes?;(c) Spider;(d) Bird-Feather;(e) Spider;(f) Insect wings
and organic debris;(g) Mosquito;(h) Organic debris;(i) Parts of insects (j) Dragon fly?(k) Some parts of insects and
organic debris and (l) Ants and organic materials.(photomicrographs by Thet Tin Nyunt; dark field, 40×)
(j)
(e)
(f)
Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71 69
Fig. 10:(a) Organic debris and gas bubbles;(b) Insect inclusions;(c) Organic debris;(d) Insect inclusion;(ef) Plants,
other organic debris and gas bubbles in Khamti amber.(photomicrographs by Thet Tin Nyunt; dark field, 40×)
Fig. 11: Representative of IR absorption spectrum (top) and Raman spectrum (bottom) of Khamti amber
(modified after Thet Tin Nyunt et al., 2020). The asterisk in the IR spectrum marks an analytical artefact
(absorption by CO2 in the air). The Raman spectrum has been corrected for strong broad-band background
luminescence.
70 Thet Tin Nyunt et al./Thai Geoscience Journal 2 (2), 2021, p. 61-71
Acknowledgements
We are very thankful to the CCOP Technical
Committee for allowing us to present this article
in the CCOP 56th Annual Meeting Thematic
Session 2020. Sincere thanks are due to Khaing
Nan Shwe Gems & Jewellery Co. Ltd. for their
generous support. U Tin Kyaw Than (Principal,
Gemmological Science Centre, Myanmar) is
thanked for his advice during the present
research. We thank Andreas Wagner for sample
preparation, Dr. Eugen Libowitzky for help with
the FTIR–ATR analyses, and Prof. Dr. Lutz
Nasdala for help with Raman analyses. Much
appreciation to Daw Gjam, U Aung Naing, Dr.
Ko Hein and also the Yangon Gems and
Jewellery Entrepreneur Association (YGJEA)
for providing financial support that enabled lead
author Dr. Thet Tin Nyunt to present the results
of this study at the at the poster session of the 36th
International Gemmological Conference (IGC,
2019) in Nantes, France. Thanks, are also
contribute to Prof. Dr. Bo Wang, Director,
Nanjing Institute of Geology and Paleontology
and Dr. Jiang Tian, China University of
Geosciences (Beijing) for identification and
discussion on fossils. Last, but not least, the
assistance of Ko Min Thiha, Daw Yi Yi Win
(DGSE) and Daw Thuzar Tun (Yangon
University) in figure arrangements is gratefully
acknowledge.
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