A minimum metal mine is a

land mine A land mine, or landmine, is an explosive weapon often concealed under or camouflaged on the ground, and designed to destroy or disable enemy targets as they pass over or near it. Land mines are divided into two types: anti-tank mines, wh ...

that is designed to use the smallest amount of metal possible in its construction. Typically, the only metal components are located inside the

fuze In military munitions, a fuze (sometimes fuse) is the part of the device that initiates its function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fu ...

mechanism which triggers detonation. Both minimum metal

anti-tank Anti-tank warfare refers to the military strategies, tactics, and weapon systems designed to counter and destroy enemy armored vehicles, particularly tanks. It originated during World War I following the first deployment of tanks in 1916, and ...

and

anti-personnel mine An anti-personnel mine or anti-personnel landmine (APL) is a form of land mine, mine designed for use against human, humans, as opposed to an anti-tank mine, which target vehicles. APLs are classified into: blast mines and fragmentation mines; ...

s exist. Some designs contain virtually no metal at all, e.g., less than a

gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram. Originally defined in 1795 as "the absolute Mass versus weight, weight of a volume ...

Methods

Low-metallic mines

This is achieved by encasing the explosive charge in a

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

en, or

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

body, with metallic components limited to the few small parts in the

which can not easily be made from other materials, such as the spring, striker tip, and shear pin. Minimum metal mines are extremely difficult to detect using conventional metal mine detectors and usually require modern techniques, such as robotic ''Multi Period Sensing'' (MPS) equipment, to identify, but it is still extremely difficult to find non-metallic mines. These techniques are usually restricted to well-funded international

mine clearing Demining or mine clearance is the process of removing land mines from an area. In military operations, the object is to rapidly clear a path through a minefield, and this is often done with devices such as mine plows and blast waves. By contr ...

organizations and major militaries, making minimum metal mines especially pernicious where they are encountered.

Non-metallic mines

Though rare, a few land mine designs (both anti-tank and anti-personnel) contain no metal whatsoever. Such mines cannot be found using metal detectors because there is no metal to detect. Typically, 100% non-metallic landmines have a plastic case and a

which comprises a glass or plastic vial containing a mixture of friction-sensitive

pyrotechnic Pyrotechnics is the science and craft of creating fireworks, but also includes safety matches, oxygen candles, explosive bolts (and other fasteners), parts of automotive airbags, as well as gas-pressure blasting in mining, quarrying, and demol ...

composition and glass powder. Downward force on the pressure plate overcomes the breaking strain of a plastic shear pin which snaps, allowing the non-metallic firing pin assembly to move. The firing pin is pushed down through a flexible plastic forcing-cone, which abruptly releases it on the other side at much higher velocity. Concentrated pressure is thereby transferred directly onto the glass vial, crushing and fracturing it. Alternatively, when the shear pin breaks, pressure on the fuze is transferred onto a plastic belleville spring which flips downwards, stabbing a non-metallic tapered pin (sometimes made from a glass ceramic) through a thin plastic membrane covering the vial of friction-sensitive pyrotechnic mixture. Either way, this action causes a flash of flame that triggers the

detonator A detonator is a device used to make an explosive or explosive device explode. Detonators come in a variety of types, depending on how they are initiated (chemically, mechanically, or electrically) and details of their inner working, which of ...

and initiates the adjacent booster which in turn

detonate Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves wit ...

s the main explosive filling.

Examples

Early examples included the German Glasmine 43, Schu-mine 42 and Topfmine used during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. These designs were either difficult or impossible to find using 1940s metal detectors. Many different types of minimum metal mines have been produced in various countries over the years. Relatively modern examples include the antitank mines M19 (United States, less than 3g of metal) and TMA-3 (

Serbia , image_flag = Flag of Serbia.svg , national_motto = , image_coat = Coat of arms of Serbia.svg , national_anthem = () , image_map = , map_caption = Location of Serbia (gree ...

, no metal) and the anti-personnel mines PRB M-409 (Belgium, less than 1g) and the

PMA-2 A Pressurized Mating Adapter (PMA) is a component used on the International Space Station (ISS) to convert the Common Berthing Mechanism (CBM) interface used to connect ISS modules to an Androgynous Peripheral Attach System#APAS-95, APAS-95 spac ...

or PMA-3 Serbia, (approx 1g non-magnetic) and VS-50 (Italy). Since the 1970s and until 1993 (when the country enacted a national landmines manufacturing ban, four years before signing the

Ottawa Treaty The Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction of 1997, known informally as the Ottawa Treaty, the Anti-Personnel Mine Ban Convention, or often simply the Mine ...

) Italy became a world leader in the manufacture of minimum metal mines; the three main Italian landmine manufacturers were mostly producing minimum-metal mines by the early 1980s. '' Valsella Meccanotecnica SpA'' manufactured the VS-50 and VS-Mk2. ''Misar SpA'' produced the SB-81 and SB-33, and ''Tecnovar Italiana SpA'' produced the TS-50, TC/3.6 and TC/6 mines.

International law

Article 4 of the 1996 Amended Protocol II to the

Convention on Certain Conventional Weapons The United Nations Convention on Certain Conventional Weapons (CCW or CCWC), concluded at Geneva on October 10, 1980, and entered into force in December 1983, seeks to prohibit or restrict the use of certain conventional weapons which are cons ...

provides that "It is prohibited to use anti-personnel mines which are not detectable, as specified in paragraph 2 of the Technical Annex."

References