![]() Hematite shows only a very feeble response to a magnetic field. Rich deposits of hematite have been found on the island of Elba that have been mined since the time of the Etruscans. Near Rydno in Poland and Lovas in Hungary red chalk mines have been found that are from 5000 BC, belonging to the Linear Pottery culture at the Upper Rhine. Hematite residues are also found in graves from 80,000 years ago. The powdery mineral was first used 164,000 years ago by the Pinnacle-Point man, possibly for social purposes. The red chalk writing of this mineral was one of the earliest in the human history. The principal use of ochre is for tinting with a permanent color. Red ochre contains unhydrated hematite, whereas yellow ochre contains hydrated hematite ( Fe 2 O 3 ![]() Ochre is a clay that is colored by varying amounts of hematite, varying between 20% and 70%. the 15th century, which originated from Ancient Greek αἱματίτης λίθος ( haimatitēs lithos, "blood-red stone"). The English name of the stone is derived from Middle French hématite pierre, which was taken from Latin lapis haematites c. The color of hematite is often used as a pigment. The name hematite is derived from the Greek word for blood αἷμα (haima), due to the red coloration found in some varieties of hematite. Hematite can also occur in the absence of water, usually as the result of volcanic activity.Ĭlay-sized hematite crystals can also occur as a secondary mineral formed by weathering processes in soil, and along with other iron oxides or oxyhydroxides such as goethite, which is responsible for the red color of many tropical, ancient, or otherwise highly weathered soils. The mineral can precipitate in the water and collect in layers at the bottom of the lake, spring, or other standing water. Gray hematite is typically found in places that have still, standing water or mineral hot springs, such as those in Yellowstone National Park in North America. Large deposits of hematite are found in banded iron formations. Maghemite is a polymorph of hematite (γ- Feģ) with the same chemical formula, but with a spinel structure like magnetite. Hematite is not only harder than pure iron, but also much more brittle. ![]() While these forms vary, they all have a rust-red streak. Hematite varieties include kidney ore, martite ( pseudomorphs after magnetite), iron rose and specularite ( specular hematite). ![]() It is mined as an important ore mineral of iron. Hematite naturally occurs in black to steel or silver-gray, brown to reddish-brown, or red colors. With this it forms a complete solid solution at temperatures above 950 ☌ (1,740 ☏). It has the same crystal structure as corundum ( Alģ). Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Feģ. Hematite ( / ˈ h iː m ə ˌ t aɪ t, ˈ h ɛ m ə-/), also spelled as haematite, is a common iron oxide compound with the formula, Fe 2O 3 and is widely found in rocks and soils. Tabular to thick crystals micaceous or platy, commonly in rosettes radiating fibrous, reniform, botryoidal or stalactitic masses, columnar earthy, granular, oolitic Metallic grey, dull to bright "rust-red" in earthy, compact, fine-grained material, steel-grey to black in crystals and massively crystalline ores
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |