App. H— Conversion Table and Glossary • 335 



and are the only source of high-aluminum chromite. 

 In the United States, they occur mostly on the Pa- 

 cific Coast in California and Alaska. 



Polychaete: a class of segmented marine worms. 



Polymetallic Sulfide: A popular term used to describe 

 the suites of intimately associated sulfide minerals that 

 have been found in spreading centers on the ocean 

 floor. 



Primary Productivity: the amount of organic matter 

 synthesized from inorganic substances in a given area 

 or a measured amount of time (e.g., gm/m^/yr). 



Processing: The series of steps by which raw material 

 (ore) is transformed into intermediate or final mineral 

 products. The number and type of steps involved in 

 a particular process may vary considerably depend- 

 ing on the characteristics of the ore and the end prod- 

 uct or products to be extracted from the ore. 



Pycnocline: a vertical gradient in the ocean where den- 

 sity changes rapidly. 



Pyrolusite: A soft iron-black or dark steel-gray 

 tetragonal mineral composed of manganese dioxide 

 (MnOa). It is the most important ore of manganese. 



Reconnaissance: A general, exploratory examination or 

 survey of the main features of a region, usually pre- 

 liminary to a more detailed survey. 



Refractory: A material of high melting point, possess- 

 ing the property of heat resistance. 



Remote Sensing: The collection of information about 

 an object by a recording device that is not in physi- 

 cal contact with it. The term is usually restricted to 

 mean methods that record reflected or radiated elec- 

 tromagnetic energy, rather than methods that involve 

 significant penetration into the earth. 



Resistivity: The electrical resistance offered by a mate- 

 rial to the flow of current, times the cross-sectional 

 area of current flow and per unit length of current 

 path; the reciprocal of conductivity. 



Resolution: A measure of the ability of geophysical in- 

 struments, or of remote-sensing systems, to define 

 closely spaced targets. 



Rhodochrosite: A rose-red or pink to gray rhombohedral 

 mineral of the calcite group: MnCOs. It is a minor 

 ore of manganese. 



Rhodonite: A pink or brown mineral of silicate- 

 manganese: MnSiOs. 



Rutile: Occurs naturally as a reddish-brown, tetragonal 

 mineral composed of impure titanium dioxide (Ti02); 

 common in acid rocks, sometimes found in beach 

 sands. 



Seafloor Spreading Center: A rift zone on the ocean floor 

 where two plates are moving apart and new oceanic 

 crust is forming. 



Seamount: A seafloor mountain generally formed as a 

 submarine volcano. 



Seismic Reflection: The mapping of seismic energy that 

 has bounced off impedence layers within the earth. 



Seismic Refraction: The transport of seismic energy 

 through rock and along impedence layers. 



Silicomanganese: A crude alloy made up of 65 to 70 per- 

 cent manganese, 16 to 25 percent silicon, and 1 to 

 2.5 percent carbon; used in the manufacture of low- 

 carbon steel. 



Sonar: Sonic energy bounced off distant objects under- 

 water to locate and range on them, just as radar does 

 with microwaves in air. 



Stainless Steel: Steel with exceptional corrosion and ox- 

 idation resistance, usually containing between 12 and 

 36 percent chromium. Chromium contents of 12 per- 

 cent are required to be corrosion resistant. Some low- 

 chromium stainless steels are produced (nine percent 

 to 12 percent), but chromium content averages about 

 17 percent. 



Stratiform Deposits: Primary chromite mineral depos- 

 its that occur as uniform layers up to several feet thick 

 similar to coalbeds. Stratiform deposits generally con- 

 tain chromite with low chromium-iron ratio, are com- 

 paratively uniform and extend over large areas. The 

 chromite occurrences in the Stillwater Complex in 

 Montana are characteristic of stratiform deposits. 



Stratigraphy: Study of the order of rock strata, their age 

 and form as well as their distribution and lithology. 



Substrate: 1) The substance on or in which an organ- 

 ism lives and grows, 2) The underlying material (e.g., 

 basalt) to which cobalt-rich ferromanganese crusts are 

 cemented. 



Succession : the gradual process of community change 

 brought about by the establishment of new popula- 

 tions of species which eventually replace the original 

 inhabitants. 



Superphosphate: One of the most important phospho- 

 rus fertilizers, derived by action of sulfuric acid on 

 phosphate rock. Ordinary superphosphate contains 

 about 18 to 20 percent phosphorous pentoxide (P2O5). 

 Triple superphosphate is enriched in phosphorus (44 

 percent to 46 percent P2O5) and is manufactured by 

 treating superphosphate with phosphoric acid. 



Synthetic Rutile: Rutile substitutes made from high- 

 grade Omenites by various combinations of oxidation- 

 reduction and leaching treatments to remove the bulk 

 of the iron. 



Taxonomy: classification of organisms into groups re- 

 flecting their similarity and differences (Kingdom, 

 Phylum, Class, Order, Family, Genus, Species). 



Thermocline: a gradient in the ocean where tempera- 

 ture changes rapidly. 



Titanium Dioxide Pigment: A white, water-insoluble 

 powder composed of relatively pure titanium dioxide 

 (Ti02) produced commercially from Ti02 minerals 



