Topic: Mineralisation of tin as cassiterite in Malaysia
Earthcache Location
This Earthcache brings you to the Muzium Geologi in Ipoh, a fascinating treasure trove of information on rocks and minerals and the role the field of geology has played in Malaysia. Admission is free, and there is ample parking on site, but do take note of the opening hours.
Monday: 9AM–12:30PM, 2–4:30PM
Tuesday: 9AM–12:30PM, 2–4:30PM
Wednesday: 9AM–12:30PM, 2–4:30PM
Thursday: 9AM–12:30PM, 2–4:30PM
Friday: 9AM–12PM, 3–4:30PM
Saturday: 9AM–5PM
Sunday: Closed
The History of Tin
Tin is the element with atomic number 50. It is a grey transition metal and one of the metals that was discovered fairly early on in the human civilisation timescale. It has chemical symbol Sn (which comes from its Latin name Stannum). Tin’s malleability and low melting point made it a very useful metal, and is often combined with copper to make bronze, one of the earliest discovered alloys of metal. Tin has played an important role throughout humanity’s history - from its use in weapons, pottery, mirrors and bells in the Bronze Age to electronic solders and food canning in the Modern Age.
Malaysia’s own history was shaped by the discovery of tin in large quantities throughout Malaya. First discovered in the 19th century, the control of tin mines and taxes on mining land became a source of political intrigue and wars between the local royalty and noblemen. It was this political drama that led to the entry of the British influence in Malaya, heralding the beginning of the British Colonial Period.
The British brought in labourers from other parts of East and South Asia to mine this precious resource from the lands they bought from the local rulers, and many Malaysians can trace their ancestry to someone who had come to this country to try to make their fortune in the tin industry. Likewise, many Malaysian cities such as Seremban, Kuala Lumpur and Ipoh can trace their foundation to the metal.
Indeed, tin mining has left an indelible mark on Malaysia, both literally and figuratively. The Kinta Valley, where you currently are, is now dotted with mining ponds, remnants of holes in the ground dug up to extract tin ore. An exhibit in the Museum explains how tin was mined in Malaysia.
Properties of Cassiterite
Cassiterite is the primary mineral from which tin is extracted. It takes its name from the Greek word for tin: “kassiteros” and has been the chief source of tin ore in the world. Originally mined in Cornwall, England, this same mineral has been discovered in large deposits around the world such as Bolivia and the Congo. Malaya was also blessed with huge deposits of this mineral which was the foundation upon which the tin mining industry was built on.
Cassiterite is often found as a minor constituent of igneous rocks (rocks that are formed from the cooling of magma from the Earth’s mantle). However, more often than not, cassiterite is not mined from the rocks itself, but within deposits downstream from the rocks. This happens as the cassiterite-containing rocks are weathered, and the eroded material are deposited in the rivers and alluvial fields downstream. Hence, the majority of the tin-mining fields in Malaysia are located in the major river valleys, such as the Kinta River Valley and Klang Valley.
Cassiterite (SnO2) presents as a dark-coloured mineral with a shiny lustre when viewed in good lighting. The crystal structure is tetragonal, with the oxygen atoms bound to the tin atom at 60 degree angles. This gives pure cassiterite crystals a beautiful and distinctive shape, and good quality samples are considered to be a precious gem.
The Earthcache Tasks
The Geology Museum in Ipoh has a number of exhibits which you can enjoy while you are there, but for the purpose of this Earthcache, look for the exhibit on Tin Mining in Malaysia. Observe the cassiterite samples on display and answer the following questions:
- Look for the “Heritage Object” (Objek Warisan) on display, which is a particularly large sample of cassiterite found nearby. Describe this sample. Also, where was it found and what is its mass?
- There are other smaller samples on display, which display cassiterite embedded in various rocks. Look for the sample from Lombong Ban Fatt Hin in Tronoh, Perak which is unique because it contains not one, but two tin-containing minerals. Besides cassiterite, what is the other mineral that it contains?
- Look for the Vein Cassiterite from Sungai Besi, Selangor. Examine the sample closely. How does the cassiterite present itself in the rock?
- On the wall opposite the sample is an information panel that describe various ore-bearing minerals. Look for the section on cassiterite, which is accompanied by a picture. What is the shape of the cassiterite? Can you explain why it is that particular shape?
- Lastly, look for a display of minerals that is usually found together with cassiterite. Grains of the minerals are placed in round containers. Identify the three minerals on the bottom row together with their chemical formulae.