4_RRL: Iron Flashcards
Discuss the physical and chemical properties of iron that make it a valuable industrial metal.
Iron (Fe) is a lustrous, ductile, malleable, silver-gray metal, strongly attracted by a magnet and easily magnetized. It is the fourth most common element in the Earth’s crust, constituting about 5% by weight. It has a relative density of 5.2, making it five times heavier than water. When exposed to air, iron oxidizes, forming rust. These properties, along with its abundance and strength, make iron crucial in construction, manufacturing, and various industrial applications.
What are the principal iron minerals found in nature, and how are they characterized?
The main iron minerals include hematite (Fe₂O₃), magnetite (Fe₃O₄), limonite (Fe₂O₃·3H₂O), goethite (FeO·OH), and siderite (FeCO₃). Hematite is reddish-brown to black with an earthy or metallic luster. Magnetite is notable for its strong magnetism and iron-black color. Limonite is a hydrated iron oxide appearing yellowish-brown. Goethite and siderite occur less frequently but are also important iron sources.
Explain the significance of skarn deposits in Philippine iron ore production.
Skarn deposits are the most important iron deposits in the Philippines. They form where limestone or calcareous sediments are intruded by younger plutonic rocks, leading to metasomatism. These deposits often contain not only iron but also gold, copper, lead, and zinc. Major skarn deposits are found in Luzon Central Cordillera, Samar, and Southern Mindanao, playing a crucial role in the country’s iron mining industry.
Describe the formation and economic importance of magnetite sand deposits in the Philippines.
Magnetite sand deposits form through the concentration of magnetite in beach and alluvial sands. These sands typically contain 15–30% magnetite, yielding about 55–60% Fe when processed. Despite the impurities of titanium and vanadium affecting smelting quality, they can enhance the concentrate’s value when present in high amounts for special steel production. Extensive deposits exist along the beaches of northern Luzon, eastern Leyte, and southwestern Negros.
How do laterite iron deposits differ from other iron ore types, and where are they commonly found in the Philippines?
Laterite iron deposits are surficial and form through the weathering of mafic and ultramafic rocks. They are classified into nickeliferous laterites (rich in nickel) and aluminous laterites (rich in alumina). Significant nickeliferous laterites are located in northern Sierra Madre, Zambales Range, and Dinagat Island. These deposits are economically valuable due to their association with nickel and aluminum production.
Assess the impact of legislation on the mining of magnetite sand in the Philippines.
The extraction of beach sand, including magnetite sand, is prohibited in the Philippines under Batas Pambansa Blg. 265 (1982). This legislation aims to protect coastal environments from erosion and ecological damage. As a result, magnetite sand mining operations must now focus on inland deposits or seek alternative methods that comply with environmental regulations.
What are sedimentary iron deposits, and why are they less economically significant in the Philippines?
Sedimentary iron deposits consist of layers of hematite and magnetite interbedded with sedimentary rocks. In the Philippines, these deposits, such as those in Camalaniugan (Cagayan) and Tinambac (Camarines Sur), are relatively small and have lower economic value compared to skarn and magnetite sand deposits. Their limited reserves and lower iron content reduce their commercial viability.
Discuss the factors contributing to the decline of commercial iron production in the Philippines after 1993.
Commercial iron production in the Philippines declined after 1993 due to several factors, including the depletion of economically viable deposits, high operational costs, environmental concerns, and competition from imported iron and steel products. Additionally, regulatory restrictions on mining operations and global market fluctuations may have discouraged investment in the local iron mining industry.
Compare and contrast the characteristics of bog iron ore and spring iron deposits.
Bog iron ore forms in wetlands through the precipitation of ferric oxides due to bacterial action, while spring iron deposits originate from mineral-rich spring waters in volcanic terrains. Bog iron ore contains high levels of impurities like manganese and clay, making it of minor economic significance. In contrast, spring iron deposits, though also minor in the Philippines, are characterized by limonite crusts and unique textures such as botryoidal formations.
