Matsubase

Matsubase is the name of a historic chrysotile asbestos mine and surrounding deposit located in Kumamoto Prefecture on the island of Kyushu, Japan. It is the type locality for several rare serpentine-group minerals and was one of Japan's notable domestic sources of chrysotile fiber during the 20th century.

Origin

The name comes from the Matsubase district (now part of Uki City) in Kumamoto, Japan. The deposit became known to Western mineralogy in the early-to-mid 20th century, and the locality gained scientific prominence when rare fibrous serpentine minerals were characterized from its serpentinite host rocks.

Significance in Asbestos Context

Although Japan's domestic asbestos production was small compared with Canada, Russia, or South Africa, mines like Matsubase contributed chrysotile to Japanese industrial products, and the locality is frequently cited in mineralogical literature used by expert witnesses. For patients whose exposure occurred through Japanese-manufactured goods, ships built in Japanese yards, or U.S. military service in occupied Japan and Okinawa, the existence of domestic Japanese sources can matter for tracing fiber provenance. Defense experts sometimes invoke unusual source localities to argue alternative exposure, so understanding where a fiber originated, and where it did not, can be relevant to causation arguments.

Example Sentence

The plaintiff's mineralogist noted that the chrysotile fibers recovered from lung tissue were consistent with commercial Canadian sources rather than the rarer Matsubase-type serpentine found in some Japanese deposits.

Related Terms

Chrysotile, Serpentine, Provenance Analysis, Type Locality, Fiber Burden Analysis, Asbestiform

Notes

• If you served in the U.S. military in Japan, Okinawa, or aboard ships repaired in Japanese yards, tell your attorney. Domestic Japanese asbestos sources may be relevant to your exposure history.
• Preserve any records of work with imported Japanese products (electronics, automotive parts, machinery, shipbuilding materials) that may have contained domestic chrysotile.
• Ask whether any fiber analysis in your case has attempted provenance attribution; the geographic source of fibers can become a contested issue when defendants argue alternative exposure.
• For most U.S. patients, Matsubase won't be directly relevant. The vast majority of commercial chrysotile in American products came from Quebec, Russia, or southern Africa.