Wolfsong
February 8th, 2006, 06:59 PM
Last summer, while out in Vancouver, I had the chance to visit a friend of mine. While there he introduced me to a marvelous mineral specimen that has been very interesting to work with. This is one of those cases where I feel that the properties found within the specimen are equally due to both the composition of the specimen itself as well as the processes involved in the development of it and where this process took place.
That being said it is known as a Manganese Nodule and comes from a deep oceanic vent off the coast of Alaska. Here is a little scientific backround on these nodules...
Growth and composition
Nodule growth is one of the slowest of all geological phenomena – in the order of a centimeter over several million years. Several processes are involved in the formation of nodules, including the precipitation of metals from seawater (hydrogenous), the remobilization of manganese in the water column (diagenetic), the derivation of metals from hot springs associated with volcanic activity (hydrothermal), the decomposition of basaltic debris by seawater (halmyrolitic) and the precipitation of metal hydroxides through the activity of microorganisms (biogenic). Several of these processes may operate concurrently or they may follow one another during the formation of a nodule.
The chemical composition of nodules varies according to the kind of manganese minerals and the size and characteristics of the core. Those of greatest economic interest contain manganese (27-30 %), nickel (1.25-1.5 %), copper (1-1.4 %) and cobalt (0.2-0.25 %). Other constituents include iron (6 %), silicon (5%) and aluminum (3%), with lesser amounts of calcium, sodium, magnesium, potassium, titanium and barium, along with hydrogen and oxygen.
Occurrence
Nodules lie on the seabed sediment, often partly or completely buried. They vary greatly in abundance, in some cases touching one another and covering more than 70 per cent of the bottom. The total amount of polymetallic nodules on the sea floor was estimated at 500 billion tons by A.A. Archer in 1981. They can occur at any depth, even in lakes, but the highest concentrations have been found on vast abyssal plains in the deep ocean between 4,000 and 6,000 meters.
Polymetallic nodules were discovered in 1868 in the Kara Sea, in the Arctic Ocean off Siberia. During the scientific expeditions of the H.M.S. Challenger (1872-76), they were found to occur in most oceans of the world. Nodules of economic interest have been found in three areas: the north central Pacific Ocean, the Peru Basin in the southeast Pacific, and the center of the north Indian Ocean. The most promising of these deposits in terms of nodule abundance and metal concentration occur in the Clarion-Clipperton Fracture Zone of the eastern equatorial Pacific between Hawaii and Central America.
And here is a picture:
60144
Although I have come to some conclusions on this nodule I'm curious if anyone else has had a chance to work with them and what thier findings were. I'll post my results in a few days and we can compare notes.
That being said it is known as a Manganese Nodule and comes from a deep oceanic vent off the coast of Alaska. Here is a little scientific backround on these nodules...
Growth and composition
Nodule growth is one of the slowest of all geological phenomena – in the order of a centimeter over several million years. Several processes are involved in the formation of nodules, including the precipitation of metals from seawater (hydrogenous), the remobilization of manganese in the water column (diagenetic), the derivation of metals from hot springs associated with volcanic activity (hydrothermal), the decomposition of basaltic debris by seawater (halmyrolitic) and the precipitation of metal hydroxides through the activity of microorganisms (biogenic). Several of these processes may operate concurrently or they may follow one another during the formation of a nodule.
The chemical composition of nodules varies according to the kind of manganese minerals and the size and characteristics of the core. Those of greatest economic interest contain manganese (27-30 %), nickel (1.25-1.5 %), copper (1-1.4 %) and cobalt (0.2-0.25 %). Other constituents include iron (6 %), silicon (5%) and aluminum (3%), with lesser amounts of calcium, sodium, magnesium, potassium, titanium and barium, along with hydrogen and oxygen.
Occurrence
Nodules lie on the seabed sediment, often partly or completely buried. They vary greatly in abundance, in some cases touching one another and covering more than 70 per cent of the bottom. The total amount of polymetallic nodules on the sea floor was estimated at 500 billion tons by A.A. Archer in 1981. They can occur at any depth, even in lakes, but the highest concentrations have been found on vast abyssal plains in the deep ocean between 4,000 and 6,000 meters.
Polymetallic nodules were discovered in 1868 in the Kara Sea, in the Arctic Ocean off Siberia. During the scientific expeditions of the H.M.S. Challenger (1872-76), they were found to occur in most oceans of the world. Nodules of economic interest have been found in three areas: the north central Pacific Ocean, the Peru Basin in the southeast Pacific, and the center of the north Indian Ocean. The most promising of these deposits in terms of nodule abundance and metal concentration occur in the Clarion-Clipperton Fracture Zone of the eastern equatorial Pacific between Hawaii and Central America.
And here is a picture:
60144
Although I have come to some conclusions on this nodule I'm curious if anyone else has had a chance to work with them and what thier findings were. I'll post my results in a few days and we can compare notes.