4_Iron Flashcards
Describe the physical properties of iron that make it an important industrial metal.
Iron is a lustrous, ductile, malleable, silver-gray metal. It is strongly attracted by magnets and is easily magnetized. It has a relative density of 5.2, making it five times heavier than water. It is the fourth most common element in the Earth’s crust and is believed to be a major component of the Earth’s core.
List and describe the principal iron minerals found in nature.
The principal iron minerals include hematite (Fe2O3), magnetite (Fe3O4), limonite (Fe2O3·3H2O), goethite (FeO.OH), and siderite (FeCO3). Each mineral varies in iron content and occurrence in different geological environments.
Why is hematite considered the most important iron ore?
Hematite is considered the most important iron ore due to its high iron content (~72.4% Fe) and widespread occurrence in both sedimentary and metamorphic rocks. It serves as a major source of iron for industrial use.
What are the different varieties of hematite and their characteristics?
Varieties of hematite include kidney ore, iron rose, martite, and specularite. Red ochre is a red earthy variety of hematite used as a pigment.
Explain the formation and characteristics of magnetite.
Magnetite is characterized by strong magnetism and may act as a natural magnet (lodestone). It has an iron-black color, metallic luster, and a black streak. It is an important iron ore due to its high iron content and magnetic properties.
Discuss the occurrence and significance of siderite as an iron ore.
Siderite, an iron carbonate mineral, is a minor ore of iron commonly found in sedimentary, hydrothermal, and metamorphic environments. Its color ranges from brownish-yellow to dark brown due to iron oxidation.
What role does goethite play in iron ore formation?
Goethite is an iron oxyhydroxide mineral and a major component of limonite. It is one of the most common weathering products of iron-bearing minerals and plays a crucial role in iron ore formation.
Differentiate between nickeliferous and aluminous laterite iron deposits.
Nickeliferous laterite iron deposits occur over ultramafic rocks rich in nickel, while aluminous laterites occur over mafic rocks high in alumina. Major nickeliferous laterites are found in northern Sierra Madre, Mindoro, and Dinagat Island Group.
Describe the geological settings of skarn deposits in the Philippines.
Skarn deposits, the most important iron deposits in the Philippines, form when limestone or calcareous sediments are intruded by younger plutonic rocks. These deposits often contain other metals like gold, copper, lead, and zinc.
What are pyrometasomatic deposits and where can they be found in the Philippines?
Pyrometasomatic deposits occur in volcanic-sedimentary sequences near volcanic rocks. They are closely associated with dioritic rocks and fault systems. Examples include deposits in Sibuguey and Camachin in the Philippines.
Explain the significance of the Larap Mine in the history of iron mining in the Philippines.
The Larap Mine is the largest and oldest iron mine in the Philippines. It has shipped over 16 million tons of iron ore and contains valuable by-products like copper, molybdenum, gold, uranium, and cobalt.
What are the main types of iron deposits found in the Philippines?
The main types of iron deposits in the Philippines include skarn, magnetite sand, laterite, sedimentary, bog, and spring deposits. Each type varies in geological setting and economic significance.
Discuss the economic importance of magnetite sand deposits in the Philippines.
Magnetite sand deposits consist of magnetite concentrations in beach and alluvial sands. They are economically important due to their iron content (55-60% Fe) and are found in northern Luzon, Leyte, and southwestern Negros.
How does the presence of telluride minerals in Thanksgiving Mine provide insights into ore formation?
The presence of telluride minerals like petzite and sylvanite in Thanksgiving Mine suggests hydrothermal fluid evolution under specific temperature-pressure conditions favorable for gold deposition.
Describe the trends in Philippine iron ore trade in 2023 and 2024.
In 2023, the Philippines exported $366M in iron ore, primarily to Japan, China, and Vietnam, while importing $542M worth of iron ore, mainly from Brazil and South Africa. In 2024, exports increased by 15.5%, while imports grew by 433%, resulting in a negative trade balance of $20.2M.
