Warta Geologi, Vol. 46, No. 3, December 2020, pp. 191–195

Discovery of agate geode and nodules at Mount Conner,
Semporna, Sabah

Elvaene James^1,2,*, Hennie Fitria W. Soehady
Erfen³, Azman A. Ghani², Angela Vidda Chuwat⁴,
Gerald Eko Ejiga², Terfa Elijah Garba²

¹ Department of Geoscience, Faculty of Earth
Science, University Malaysia Kelantan, 17600 Jeli, Kelantan, Malaysia

² Department of Geology, Faculty of Science,
University of Malaya, 50603 Kuala Lumpur, Malaysia

³ Faculty of Science and Natural Resources, University
Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia

⁴ School of Physics, University Sains Malaysia,
11800 Penang, Malaysia

* Corresponding author email address: elvaene@umk.edu.my

Abstract:
An exposure of agate geode and nodules in Mount Conner, Sabah, provides an
essential aspect to the geological formation in Semporna. This paper briefly
report results from petrography analyses on the agate geode and nodules and its
significance to the volcanic rocks and sedimentary rocks formation in Mount
Conner. The geode and nodules can be divided into agate, and nodules and most
of them are sub-rounded. Nodules are usually small in size and display brownish
colour. It commonly occurs in volcanic rocks (dacite and rhyolite) and
contained amygdale filled by secondary mineral such as microcrystalline and
macrocystalline quartz. In contrast, sedimentary rocks in Mount Conner contain both
nodules and geodes, which nodules shows similar characteristic with nodules in
volcanic rocks and geodes contained empty vesicles or spaces surrounded by
colourless to milky white quartz crystals. Both geode and nodules exhibit
conchoidal fracture, while geode shows vesicle features and nodules in volcanic
rocks show amygdale texture. The formation of geodes and nodules in Mount
Conner might as result of precipitation under low temperature from hydrothermal
solution.

Keywords:
Geode, Mount Conner, nodule, Semporna

Abstrak:
Penemuan geod akik dan nodul di Gunung Conner, Sabah, telah memberikan aspek
yang penting kepada formasi geologi di Semporna. Kertas ini secara ringkasnya
melaporkan hasil analisis petrografi terhadap geod akik dan nodul, dan kepentingannya
terhadap formasi batuan volkanik dan batuan sedimen di Gunung Conner. Geod akik
dan nodul boleh dibahagikn kepada akik, kalsedoni dan nodul, serta bersifat
separa bulat. Ciri-ciri yang terdapat pada nodul yang tersingkap pada batuan
volkanik (dasit dan riolit) ialah ia bersifat padat dengan tiada ruang diantara
nodul, berwarna kecoklatan dan mempunyai saiz-saiz yang kecil. Manakala, batuan
sedimen di Gunung Conner pula mengandungi kedua-dua jenis seperti nodul dan
geod. Nodul mempunyai ciri-ciri seperti yang tersingkap pada batuan volkanik
dan geod pula mempunyai vesikel didalamnya yang turut mengandungi kristal
kuarza yang tidak berwarna dan berwarna putih susu. Kedua-dua geod dan nodul
mempunyai retakan konkoidal dan tekstur amigdal. Pembentukan geod dan nodul di
Gunung Conner mungkin disebabkan oleh mendakan dibawah suhu yang rendah
daripada larutan hidrotermal.

Kata
kunci: Geod, Gunung Conner, nodul, Semporna

DOI :
https://doi.org/10.7186/wg463202003

ISSN
0126–5539; e-ISSN 2682-7549