Trinitite—the atomic rock

Abstract

On 16 July 1945, the first atomic bomb was detonated at the Alamogordo Bombing range in New Mexico, USA. Swept up into the nuclear cloud was the surrounding desert sand, which melted to form a green glassy material called 'trinitite'. Contained within the glass are melted bits of the first atomic bomb and the support structures and various radionuclides formed during the detonation. The glass itself is marvelously complex at the tens to hundreds of micrometre scale, and besides glasses of varying composition also contains unmelted quartz grains. Air transport of the melted material led to the formation of spheres and dumbbell shaped glass particles. Similar glasses are formed during all ground level nuclear detonations and contain forensic information that can be used to identify the atomic device.At 05:29:45 am local time on Monday, 16 July 1945, the nuclear age began. In a most graphic example of Einstein's famous equation (E = mc 2 or the original form m = L/V 2 where L = mass and V = the speed of light) a plutonium bomb, referred to as the 'Gadget', with a yield of 21 kilotons (equivalent to the explosive power of 21 000 tons of TNT) was detonated ( Fig. 1) at the Alamogordo Bombing range, 210 miles south of Los Alamos, New Mexico. The genie was out of the bottle and has been our uneasy companion ever since. One of the products of this nuclear explosion was a green glassy material formed by melting of the surrounding desert sand. Robert Oppenheimer had chosen the name 'Trinity' for the nuclear test and the name 'trinitite' was adopted for this green glassy material. The nuclear explosionThere are two fissionable isotopes (U-235 and Pu-239) that can be used to make atomic (fission) bombs. In both cases the basic principle is the same. A neutron interacts with a nucleus which leads to an increase in atomic mass and an unstable nucleus that splits into several pieces (fission fragments) + neutrons with a concomitant release in energy due to a loss in mass. The 235 U fission reaction is: U-235 + neutron → U-236 → fission fragments + neutrons + energyThe ejected neutrons cause further fission events leading to a chain reaction. For an explosive nuclear reaction billions of fission events need to occur in microseconds. The key is to have a sufficient mass of U-235 or Pu-239 in close proximity for this explosive reaction to occur.Two types of nuclear weapons were developed near the end of World War II. One, the 'gun type' consisted of an enriched uranium (U-235) bullet that was fired at an enriched uranium spike. The impact of these two pieces of enriched uranium produced the necessary mass density for a thermal nuclear explosion. Physicists were convinced that this type of bomb would work and only one was built and subsequently dropped on Hiroshima, on 6 August 1945. Fig. 1. The only known colour photograph of the Trinity Test.

Postdetonation nuclear debris for attribution

“…Geologically the site is in the northern Tularosa Basin, composed of alluvial, aeolian, and volcanic materials dominantly related to past marine and mountain-building episodes and subsequent erosion, leaching, and alteration. Minerals present in the local rocks and sediments include arkosic sand, quartz, feldspars (partially sericitized microcline and albite plagioclase), carbonates (e.g., calcite, trona, aragonite, and dolomite), sulfates (e.g., gypsum, selenite, bassanite, mirabilite, hexahydrite, thenardite, bloedite, and anhydrite), chlorides (halite, sylvite, and bischofite), hornblende, olivine, and clays (kaolinite and illite), magnetite, ilmenite, augite, and both meteoritic and volcanic dust (4,(7)(8)(9). Although the general area southward at the White Sands National Monument is known for its gypsum dunes, these tend to grade into higher quartz content northward (7).…”

Production of Synthetic Nuclear Melt Glass

“…It is anticipated that the melting process will affect the distribution of uranium and other elements within the glass. 3,10,12 The quantity of quartz remaining in the melted samples serves as a monitor to optimize the melting temperature and time in the furnace 5 . It is assumed that a method which produces the appropriate degree of amorphousness in a sample initially containing quartz will produce a similarly amorphous sample when other minerals are included in the precursor.…”

“…In general, quartz is the only mineral found in the melt glass. 10,12 Also, quartz sand is a common component of asphalt and concrete which will be important in the formation of urban nuclear melt glass. …”

“…This formulation was developed by examining previously reported compositional data for trinitite. 10 The mass fractions reported here were determined by averaging the mass fractions for several different trinitite samples. 10 The "missing" mass (the fractions to not sum to unity) exists to allow for some flexibility when adding fuel, tamper, and other constituents.…”

“…10 The mass fractions reported here were determined by averaging the mass fractions for several different trinitite samples. 10 The "missing" mass (the fractions to not sum to unity) exists to allow for some flexibility when adding fuel, tamper, and other constituents. Our independent analysis of several trinitite samples suggests that quartz is the only mineral phase surviving in trinitite.…”