IRON Flashcards
It is the most common element on Earth by mass, forming much of Earth’s outer and inner core.
Iron (Fe)
Iron constitutes about ___ of the Earth’s crust and is the fourth most abundant element.
5%
Chemical Formula of Hematite
Fe2O3
Magnetite chem formula
Fe3O4
Color: Typically black to steel or silver-gray, brown to reddish-brown, or red.
Hematite
Properties: Metallic to earthy luster, high density, and no cleavage. Hematite is the most important iron ore.
Hematite
Color: Black or brownish-black with a metallic luster.
Magnetite
Properties: Strongly magnetic, the densest of the iron ores. Forms in both igneous and metamorphic rocks.
Magnetite
Limonite chem formula
FeO (OH)n H2O
Color: Yellow to dark brown.
Properties: Amorphous, displaying variable hydration; often recognized by its yellowish-brown streak. Forms in many iron deposits.
Limonite
Goethite chem formula
FeO (OH)
Color: Yellowish-brown to dark brown.
Properties: Forms under oxidizing conditions as a weathering product of iron minerals. Recognizable by its characteristic brownish streak.
Goethite
Siderite chem formula
FeCO3
Color: Yellowish to brownish.
Properties: Crystalline, reacts to cold dilute hydrochloric acid. Forms in sedimentary and hydrothermal environments as well as in carbonatites.
Siderite
Iron deposits are formed in various geological settings and ages, ranging from the ____ to the __________.
Precambrian to the Cenozoic
________ form at the boundary between igneous and sedimentary rocks through metasomatism, where hot, mineral-laden fluids alter the composition of the rock, leading to ore mineralization.
Economic Significance: High-grade iron ore, potential for copper and gold by-products.
Skarn deposits
These deposits are noted for their complex chemistry and varied mineralogy, including ____, _____, and _____, often associated with copper, gold, and other metals.
garnet, pyroxene, and magnetite,
Key locations of Skarn iron deposits
Larap (Camarines Norte)
Central Cordillera
__________ are formed by the erosion of igneous and metamorphic rocks, with magnetite being concentrated by wave and current action in coastal environments.
Economic Significance: Source of iron for the steel industry, with low-cost extraction methods.
Magnetite sand deposits
Key Location of magnetite sand deposits
Northern and Western coasts of Luzon (Ilocos Region and Cagayan Valley)
Laterite sequence
Ferricrust
Limonite zone (Hematite)
Limonite zone (Goethite)
Clay
Saprolite
Unweathered ultramafic rocks
Key Locations of Laterite deposits
Surigao, Palawan, and Davao regions (Nickeliferous)
_______, also known as banded iron formations (BIFs), consist of alternating layers of iron-rich minerals and silica or shale. They are primarily formed through the chemical or biological precipitation of iron from seawater.
Economic Significance: Generally lower grade, but significant due to sheer volume and low impurities.
Sedimentary iron deposits
_________ are types of iron formations that occur in wetlands (bogs) or as outputs of mineral springs.
Characterized by the direct precipitation of iron minerals from water, leading to the accumulation of iron-rich sediments or crusts.
Bog and spring deposits
The deposit is characterized by a complex association of iron, copper, and molybdenum, formed through skarnification processes involving the intrusion of magmatic fluids into carbonate rocks, leading to the alteration and mineralization of the surrounding rocks.
Larap Fe-Cu-Mo Skarn Deposit (Camarines Norte, Luzon)
