IRON

Question 1

It is the most common element on Earth by mass, forming much of Earth’s outer and inner core.

Answer 1

Iron (Fe)

Question 2

Iron constitutes about ___ of the Earth’s crust and is the fourth most abundant element.

Answer 2

5%

Question 3

Chemical Formula of Hematite

Answer 3

Fe2O3

Question 4

Magnetite chem formula

Answer 4

Fe3O4

Question 5

Color: Typically black to steel or silver-gray, brown to reddish-brown, or red.

Answer 5

Hematite

Question 6

Properties: Metallic to earthy luster, high density, and no cleavage. Hematite is the most important iron ore.

Answer 6

Hematite

Question 7

Color: Black or brownish-black with a metallic luster.

Answer 7

Magnetite

Question 8

Properties: Strongly magnetic, the densest of the iron ores. Forms in both igneous and metamorphic rocks.

Answer 8

Magnetite

Question 9

Limonite chem formula

Answer 9

FeO (OH)n H2O

Question 10

Color: Yellow to dark brown.
Properties: Amorphous, displaying variable hydration; often recognized by its yellowish-brown streak. Forms in many iron deposits.

Answer 10

Limonite

Question 11

Goethite chem formula

Answer 11

FeO (OH)

Question 12

Color: Yellowish-brown to dark brown.
Properties: Forms under oxidizing conditions as a weathering product of iron minerals. Recognizable by its characteristic brownish streak.

Answer 12

Goethite

Question 13

Siderite chem formula

Answer 13

FeCO3

Question 14

Color: Yellowish to brownish.
Properties: Crystalline, reacts to cold dilute hydrochloric acid. Forms in sedimentary and hydrothermal environments as well as in carbonatites.

Answer 14

Siderite

Question 15

Iron deposits are formed in various geological settings and ages, ranging from the ____ to the __________.

Answer 15

Precambrian to the Cenozoic

Question 16

________ 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.

Answer 16

Skarn deposits

Question 17

These deposits are noted for their complex chemistry and varied mineralogy, including ____, _____, and _____, often associated with copper, gold, and other metals.

Answer 17

garnet, pyroxene, and magnetite,

Question 18

Key locations of Skarn iron deposits

Answer 18

Larap (Camarines Norte)
Central Cordillera

Question 19

__________ 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.

Answer 19

Magnetite sand deposits

Question 20

Key Location of magnetite sand deposits

Answer 20

Northern and Western coasts of Luzon (Ilocos Region and Cagayan Valley)

Question 21

Laterite sequence

Answer 21

Ferricrust
Limonite zone (Hematite)
Limonite zone (Goethite)
Clay
Saprolite
Unweathered ultramafic rocks

Question 22

Key Locations of Laterite deposits

Answer 22

Surigao, Palawan, and Davao regions (Nickeliferous)

Question 23

_______, 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.

Answer 23

Sedimentary iron deposits

Question 24

_________ 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.

Answer 24

Bog and spring deposits

Question 25

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.

Answer 25

Larap Fe-Cu-Mo Skarn Deposit (Camarines Norte, Luzon)