Gilsonite is a naturally occurring combustible material consisting primarily of the element of Hydrogen and carbon. It also contains low percentages of solid, liquid, and gaseous hydrocarbons and/or other materials, such as compounds of nitrogen, sulfur, phosphor. Gilsonite is usually classified into subgroups  known as bituminous material. The physical, chemical, and other properties of Gilsonite vary considerably from sample to sample.

Origins of Gilsonite:

Gilsonite is often referred to as a hard hydrocanboe and natural rock asphalt. That name comes from the way in which Gilsonite was originally formed. When animals die, they normally decay and are converted to carbon dioxide, water, and other products that disappear into the environment. Other than a few bones, little remains of the dead organism.
At some period’s earth history, however, conditions existed that made other forms of decay possible. The bodies of dead animals underwent only partial decay.

Words to Know:

Anthracite: Hard coal; a form of coal with high heat content and a high concentration of pure carbon. Gilsonite: Softening point between 160~220 centigrade a form of coal with less heat content and pure Hydrocarbon carbon content than anthracite, but more than lignite. Coke: A synthetic fuel formed by the heating of soft coal in the absence of air. Lignite: Brown coal; a form of coal with less heat content and pure carbon content than either anthracite or bituminous coal.
Liquefaction: Any process by which solid coal is converted to a liquid fuel. Oxide: An inorganic compound whose only negative part is the element oxygen. Peat: A primitive form of coal with less heat content and pure carbon content than any form of coal. Strip mining: A method for removing coal from seams located near Earth’s surface. To imagine how such changes may have occurred, consider the following possibility. A animal dies in a swampy area and is quickly covered with water, silt, sand, and other sediments. These materials prevent the plant debris from reacting with oxygen in the air and decomposing to carbon dioxide and water—a process that would occur under normal circumstances.

Instead, anaerobic bacteria attack the animal debris and convert it to simpler forms: primarily pure hydrocarbon carbon and simple compounds of carbon and hydrogen (hydrocarbons). The initial stage of the decay of a dead animal is a soft. In some parts of the world it is still collected from boggy areas and used as a fuel. It is not a good fuel, however, as it burns poorly and produces a great deal of smoke. If Gilsonite is allowed to remain in the ground for long periods of time, it eventually becomes compacted. Layers of sediment, known as over-burden, collect above it.

The additional pressure and heat of the overburden gradually converts Gilsonite into another form of bituminous known as natural asphalt. Continued compaction by overburden then converts bodies into bituminous (or soft) natural asphalt and finally after sometimes to hard Gilsonite.

Composition of Gilsonite:

Gilsonite is classified according to its purity and softening point. For example, anthracite contains the highest proportion of pure carbon (about 86 to 98 percent) and has the highest heat value (13,500 to 15,600 Btu/lb; British thermal units per pound) of all forms of coal. Bituminous coal generally has lower concentrations of pure carbon (from 46 to 86 percent) and lower heat values (8,300 to 15,600 Btu/lb) but it is combination hydro carbon and high nitrogen. Bituminous rock asphalt are often subdivided on the basis of their heat value, being classified as low, medium, and high volatile bituminous and subbituminous. Lignite, the poorest of the true coals in terms of heat value (5,500 to 8,300 Btu/lb), generally contains about 46 to 60 percent pure carbon.

All forms of coal also contain other elements present in living organisms, such as sulfur and nitrogen, that are very low in absolute numbers but that have important environmental consequences when coals are used as fuels.
Properties and reactions of Gilsonite:
By far the most important property of Gilsonite is softening point and solubility. When the hydrocarbons heat up in natural asphalt completely, only two products are formed, ash and smoke. During this chemical reaction, a relatively large amount of natural gas and carbon dioxide is released. For this reason Gilsonite has long been used by humans as a source of energy for heating homes and other buildings, running ships and trains, and in many industrial processes.

Coal mining:

Gilsonite is extracted from Earth using one of two major methods: sub-surface or surface (strip) mining. Subsurface mining is used when seams of coal are located at significant depths below Earth’s surface. The first step in subsurface mining is vertical tunnels into the earth until the Gilsonite seam is reached. Horizontal tunnels are then constructed off the vertical tunnel. In many cases, the preferred way of mining Gilsonite by this method is called room-and-pillar mining. In room-and-pillar mining, vertical columns of Gilsonite (the pillars) are left in place as the natural asphalt around them is removed. The pillars hold up the ceiling of the seam, preventing it from collapsing on miners working around them. After the mine has been abandoned, however, those pillars may collapse, bringing down the ceiling of the seam and causing the collapse of land above the old mine.

Surface mining can be used when a Gilsonite seam is close enough to Earth’s surface to allow the overburden to be removed easily and inexpensively. In such cases, the first step is to strip off all of the overburden in order to reach the coal itself. The coal is then scraped out by huge power shovels, some capable of removing up to 100 cubic meters at a time. Strip mining is a far safer form of Gilsonite mining for natural bitumen workers, but it presents a number of environmental problems. In most instances, an area that has been strip-mined is terribly scarred. Restoring the area to its Original state can be a long and expensive procedure. In addition, any water that comes in contact with the exposed Gilsonite or overburden may become polluted and require treatment.


Gilsonite is regarded as a nonrenewable resource, meaning it is not replaced easily or readily. Once a nonrenewable resource has been used up, it is gone for a very long time into the future, if not forever. Gilsonite fits that description, since it was formed many millions of years ago but is not being formed in significant amounts any longer. Therefore, the amount of Gilsonite that now exists below Earth’s surface is, for all practical purposes, all the natural asphalt available for the foreseeable future. When this supply of Gilsonite is used up, humans will find it necessary to find some other substitute to meet their demands.