Tin Mining in Hong Kong?

Tymon Mellor: In February, 1951 The International Tin Study Group, an industry body for the tin industry wrote to the Hong Kong Government requesting information about tin mining activity in the territory. A report  by the US Office of International Trade on Hong Kong economic activity in 1949 had indicated that Hong Kong had an annual tin ore production of 800 tons and 584 tons of tin slabs. The tin study group were unaware that mining and smelting of tin was taking place in Hong Kong. This also came as a surprise to the Hong Kong Government who was confident that there were no tin mines in the territory, or as later clarified, no registered tin mines operating in the territory since World War II. So where did the tin come from ? This article aims to unravel the mystery.

What is the Tin Ore ?

The first thing to note is that the mineral ore for tin is cassiterite, an opaque crystal found in granitic intrusions into the Tai Mo Shan porphyry. Typically, the deposits are found in quartz veins and as this weathered to clays, the tin ore accumulates in the residual soils, to be washed down streams and accumulate near the valley sides and in pockets in the stream bed.

A review of CEDD’s web site advises that “Cassiterite [S_nO₂] has been noted in several areas, such as Sheung Tong, Needle Hill, and Devil’s Peak, but has never been exploited commercially.”

The ‘Geology of the Western New Territories – Memoir No 3’, notes that in the vicinity of Sheung Tong “weathered granite bed-rock is said to contain significant cassiterite concentration and had also yielded some gold.”. It also notes that “cassiterite bearing alluvial placer deposits in the Kam Tin plain”. So now not only do we have tin, we also have gold!

History of Hong Kong Tin

Back in 1898, with the leasing of the New Territories to the British, a survey was undertaken to see what the new lands contained. Under Mr Stewart Lockhart, a party was organised to explore and inspect the new lands. The Director of the Public Works Department, Mr Ormsby prepared a report on the geology of the New Territories. He noted, “The natives also speak of alluvial tin being found.”

Nothing of relevance is recorded until 1952 when the annual report of the District Commissioner for the New Territories noted “Trouble was experienced with the licensees of a pre-war tin mine at the south end of the Shap Pat Heung, in the Yuen Long District, who allowed a huge accumulation of silt to foul the irrigation system here.”

The ‘Geology of Hong Kong’ by Professor Davis of Hong Kong University provides some clear guidance on the location of the tin finds, along with a map.

The book notes that “There is no record of tin having been mined in Hong Kong. However…” and then describes two locations where prospecting had identified cassiterite. The first is in Kam Tin, at the back of the valleys at the base of the foot hills. Samples from the alluvial soils “yielded 8 to 16 ounces of cassiterite to a 100 pounds of placer deposit”. The second and more promising location was at Sheung Tong, the now abandoned village in the hills north of Tsuen Wan. Massive quartz dykes over 300mm thick had been identified in the hills surrounding the village which was situated in a small basin where the land cultivated for rice. An analysis of the twelve soil samples taken over 2.5 hectares of land yielded 1.25% to 2.5% of cassiterite, equivalent to 45 tonnes over the whole area.

Given that cassiterite has a specific gravity of around 7, extraction from the soil used a flushing and panning process, mixing the material with water and letting the heavy components sink to the bottom. This would also reveal the gold that has been associated with the location. Professor Davis’ notes describes “seen a sample of gold bearing gravels from a district in the New Territories which appeared to have a high percentage of natural gold”. However, he did not reveal the location.

Back to the Tin Study Group

After some research, the Hong Kong Government got to the bottom of the Tin Study Group letter and responded at the end of August, 1951. The Treasury published quarterly figures for mineral production, based on royalties paid, and this included a small quantity of tin. The American Consular-General had reported these numbers but in error, transcribed lbs to tons. The corrected figures between 1945 to 1951 were provided to the tin council.

If you examine the Mines section of the Hong Kong Annual Report for 1953, the last item on the Type of Mine schedule is a surprise “Underground, Tin, 155.70 lbs”. Thus, tin continued to be produced in a small quantity, but where did the tin come from?

Where does Tin Come From ?

With no official tin mine, who was then paying the royalty on tin production?

In addition to the alluvial Tin ore, it is also found associated with other minerals and is commonly a secondary ore in the mining process. In the ‘Economic Geology of the Hong Kong’, when discussing Wolframite, it states that “Associated minerals are molybdenum, cassiterite, pyrite, quartz, orthoclase, fluorite, beryl, zircon, sphene, garnet, muscovite and biotite”. Thus, the recorded tin was probably a secondary product from the Wolframite workings at Needle Hill and other sites.

There is however one more explanation and this may explain why the records use the term ‘Tin Slab’. As recorded in a file note by “A.S 10” in the Government Records “I understand that tin is imported from Malaysia and is mixed here with the Chinese tin to raise the quality of the latter up to a suitable standard for export. If some of the local tin is illegally mined I suppose it is mixed with the Malaysian and Chinese”.

Thus, the tin royalties were paid on minerals extracted as a secondary product from Needle Hill mine or as a local mineral refining process. Either way, they were not significant quantities and there were no major tin mining activities in Hong Kong.

Source

• Hong Kong Public Records HKRS 41-6739-1 Tin Mining In Hong Kong
• CEDD The Geology of Hong Kong
• Geology of the Western New Territories – Memoir No 3, 1989
• Report by Mr Stewart Lockhart on the Extension of the Colony of Hong Kong, 8^th October, 1898
• Report on NT, South China Morning Post 23^rd September, 1952
• The Geology of Hong Kong, S G Davis, 1952
• Economic Geology of Hong Kong, S G Davis, 1964

This article was first posted on 15th October 2017.

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