Gold has been actively produced since the old days in Japan.
It is recorded that gold dust was gathered
in Miyagi prefecture in 749. In the twelfth century, Oshu-Fujiwara dynasty formed an
independent kingdom, mainly on Hiraizumi, in the northeast region of Japan. And it
depended on the gold dust,
which was the local special product. If gold
dust was found by a curve of a river accidentally, placer gold
was mined at the vicinity.
In the times when Kublai Khaan governed China, Marco Polo
(Italian) wrote that Japan was "a country
of gold" in his memoirs.
The Middle Ages
Abe gold mine (central part of Honshu) was
owned by the Imagawa family in 1472. Sedimentary
gold deposits were mined there at first.
These deposits are divided into the two following
1."Kawakin":. placer gold in rivers and streams.
2."Shibakin":. placer gold in sand under a gravel layer
of terrace deposit.
At these deposits, sand including gold dust
was carried away on straw mats, and heavy
gold dust of a specific weight, which sunk
to the bottom, was gathered. If a "Shibakin"
deposit had a large-scale, miners dug the
basement gallery. Such miners were considered
to be part of a special engineering group.
And miners innovated techniques to
the following type of deposit.
3."Yamakin":. Quartz vein including gold.
Gold was extracted from ore by "cupellation".
Gold ore was crushed into powder, and it
was mixed with lead. And it was burnt on
a plate made from animal bone. Lead was oxidized or melted into a plate, and
gold was left. After that, Europeans came
to Japan and taught Japanese the amalgamation.
The main gold mines at final stage of the
Middle Ages in Japan were Kurokawayama, Sado, Abe, Toi, and Takatama etc.
Gold veins were found by looking at upper
streams of placer gold.
However, as veins decreased, miners
to search veins by observing the topography,
the hue or plants in mountains. Some of them made explanations based on
their experiences and on the interacting
principles of Yin and Yang.
Some of these methods and explanations are
reasonable and have meaning, but some are
superstitious and fanatical. The primitive,
absurd and delusive nature worship has been
believed in Japan, and it is powerful, for
example as "Shinto", even now.
Therefore, people had doubtfully associated
with such prospectors.
Prospectors of ore veins are called "Yamashi"
in Japan. This word has other meanings (speculator,
swindler etc.) by the above reasons.
However, Shin-en Sato (1769-1850) is appreciated
by his detailed natural observation of mining
areas, even now.
The Modern Ages
The modernization in technology had a large
influence in the development of mining. However, it took a long time to install geological
knowledge for the exploration of ore deposits.
In Japan, around 1874, less than 100kg of gold was produced. However, it produced 500kg, in 1887, and
1200kg in 1898. It was immediately due to
the progress of refinement technology.
In 1898, placer gold was discovered in Bankenai,
Hokkaido. Gold rush occurred in Hokkaido.
Gold dust collectors gathered at the Sea
of Okhotsk coast. Farmers and fishermen sometimes
looked for placer gold, too. It is recorded
that 200g of gold was taken on a daily basis.
But, just after the discovery,all of gold dust was taken.
Kisaburo Imahori was interested in many kinds
of ore. His specimens were enormous. And
he noticed that quartz grains were often
with placer gold along the rivers in Hokkaido.
He obtained some quartz samples from the
Mobetsu river, and he explored along the
river. Imahori thought that there were gold
veins in the upper streams of the Mobetsu
river. He told Eizo Okino (fisherman) about
his thought. And Okino discovered an outcrop
of gold ore. This developed into the Konomai mine.
The price of gold did not change as much
as other prices, because it could be changed
into paper money. The production decreased
in the time when prices of general commodities
Large gold deposits were sketched in detail.
However, it was difficult to observe the
total images of the deposits. Even if the geological factor of a place was similar
to some gold deposits, it might be uneconomical
in the case of the low gold component. Therefore,
it was difficult to discover a promising
deposit by only thinking of the geological situation of the
A kind of massive sulfide ore, including
Cu, Pb, Zn, is known in English by its Japanese
name "Kuroko" (black ore). It often includes gold
and silver. But it was known after World
War II that the ore was formed by submarine
dacitic volcanic activity in neogene.
Mr.Mishima was a farmer in Hiroshima prefecture,
western area in the Main Island of Japan.
He was curious about not only agriculture but also mining. He was testing many kinds of limestone and
agalmatolite in 1949. He found that a white vein in a new garden consisted of
quartz and some gold in 1953. He was exploring in the mountains for several
years, and found a new promised outcrop.
He opened a new gold mine, called Kabutoyama
Mine, in 1963. The gold deposits are white
quartz veins in the Paleozoic.
The Hishikari gold vein deposit, in Kyushu, was found
in 1981. It has highly prized gold ore, and
is still being mined at present. The deposit
was formed with Tertiary and Quaternary volcanic
Therefore some of the unknown gold deposits
may be formed with new volcanoes.
Current Promising Areas
We are interested in the South Fossa Magna.
The Fossa Magna which means "huge ditch"
According to the recent theory, there
a huge geological crack in the middle
the ditch, in the Main Island of Japan,
some magma chambers may have risen.
The east area of the Asian Continent
almost 25 million years ago, and there
a lot of cracks. Huge amount of lava
from the cracks. These volcanic activities
made gold veins in the Sado mine that
produced the second highest amount
in Japan. In general, gold veins, which
formed by volcanic activity on land,
high gold contents with a large scale.
The Sea of Japan had begun to open
16 million years ago. And Fossa Magna
the sea. The volcanic activity continued
at the bottom of the sea. Kuroko deposits
were formed at this time.
And Hokkaido Island has some promising
We are analyzing the data and extracting
detailed survey areas in the island.