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| Limonite | |
|---|---|
| Color | Various shades of brown and yellow |
| Crystal habit | Fine grained aggregate, powdery coating |
| Cleavage | Absent |
| Fracture | Uneven |
What are the characteristics of limonite?
Limonite does not form in crystals. It occurs amorphous in earthy, massive, botryoidal, mammilary stalactitic, and fibrous form. May also form as a pseudomorph after other minerals, especially Pyrite, Siderite, and Marcasite. Becomes magnetic when heated. As a secondary mineral formed from the alteration of iron minerals.
What is the difference between Hematite and limonite?
While the first iron ore was likely meteoric iron, and hematite was far easier to smelt, in Africa, where the first evidence of iron metallurgy occurs, limonite is the most prevalent iron ore. Before smelting, as the ore was heated and the water driven off, more and more of the limonite was converted to hematite.
How did limonite get its name?
Before modern mineral analysis, the name " limonite " was given to many of the yellowish to yellowish brown iron oxides produced during the weathering of iron-bearing rocks or deposited as bog, lake, and shallow marine sediments. Researchers who studied "limonite" discovered that it is amorphous and has a variable composition.
Is fibrous limonite a pseudomorph?
Much Limonite, especially the fibrous type, is either Goethite or alter ed Goethite that absorbed water in its chemical structure. Limonite commonly forms as a pseudomorph over other minerals, especially Pyrite, Marcasite and Siderite.
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How do you identify limonite?
Limonite will leave a yellow-to-brown streak, whereas haematite produces a red streak. Two different forms of haematite both leaving a rust-red streak. This is an easily-recognised form of iron oxide, haematite. The rounded, bulbous form is described as 'botryoidal', meaning grape-like in Greek.
What streak is limonite?
Limonite usually has a dull luster and may vary in hardness from chalky or clay-like to almost that of steel. It has a distinctive yellowish-brown streak.
What type of mineral is limonite?
Description: Limonite is a general term for a mixture of fine-grained iron oxides, generally dominated by goethite, but also possibly containing hematite, lepidochrocite and other minerals. It forms from the weathering of other iron minerals, and may be precipitated by iron rich surface or ground water.
Is hematite a cleavage or fracture?
HematiteCleavageNone, may show partings on {0001} and {1011}FractureUneven to subconchoidalTenacityBrittleMohs scale hardness5.5–6.525 more rows
What is the cleavage of Galena?
GalenaCleavageCubic perfect on {001}, parting on {111}FractureSubconchoidalTenacityBrittleMohs scale hardness2.5–2.7523 more rows
What is limonite staining?
Limonite commonly forms as a pseudomorph over other minerals, especially Pyrite, Marcasite and Siderite. These pseudomorphs are very identifiable by their partial rusting look and yellow staining.
What is limonite crystal shape?
Science & Origin of Limonite It can crystallize in many forms, most notably as a mass or cubic occurrence, but also as botryoidal and even pseudomorphs (secondary minerals replacing a crystal's original compound; the word translates to “false form”).
What is the texture of limonite?
Limonite mineral specimens from the famous Cooper Peedy deposits, Australia. These samples exhibit excellent brown colouration, banded with yellow and have a typical earthy texture expected.
Is limonite metallic or non metallic?
LimoniteTypeMineralLusterMetallic / Nonmetallic Dull earthyHardness2 – 2.5 approx. = FingernailCleavageNoneStreakYellow Brown1 more row
How do you know if a mineral is cleavage or fracture?
If minerals break smoothly, along predetermined planes, the minerals are said to have cleavage. If a mineral does not have any degree of cleavage, it is said to have an irregular breakage pattern called fracture.
What is the definition of limonite?
Definition of limonite : a native hydrous ferric oxide of variable composition that is an ore of iron.
Does malachite have cleavage or fracture?
MalachiteCleavagePerfect on {201} fair on {010}FractureSubconchoidal to unevenMohs scale hardness3.5–4LusterAdamantine to vitreous; silky if fibrous; dull to earthy if massive21 more rows
Is limonite metallic or non metallic?
LimoniteTypeMineralLusterMetallic / Nonmetallic Dull earthyHardness2 – 2.5 approx. = FingernailCleavageNoneStreakYellow Brown1 more row
Is limonite a fluorescent?
Limonite, Calcite Iron content in this kind of ore ca. 25 - 48 %. - On the top side a thin crust of Calcite crystals, fluorescent and phosphorescent.
What is the texture of limonite?
Limonite mineral specimens from the famous Cooper Peedy deposits, Australia. These samples exhibit excellent brown colouration, banded with yellow and have a typical earthy texture expected.
What color is limonite?
brownish-blackLimonite includes the minerals goethite, akaganeite and lepidocrocite. Limonite forms mostly in or near oxidized iron and other metal ore deposits, and as sedimentary beds. Depending upon the content of hydrated iron oxide, the color of limonite varies from yellow to brownish-black.
What is the name of the limonite?
Names. Limonite is named for the Greek word λειμών (/leː.mɔ̌ːn/), meaning "wet meadow", or λίμνη (/lím.nɛː/), meaning “marshy lake” as an allusion to its occurrence as bog iron ore in meadows and marshes. In its brown form it is sometimes called brown hematite or brown iron ore. In its bright yellow form it is sometimes called lemon rock ...
What is limonite made of?
Limonite. Limonite ( / ˈlaɪmənaɪt /) is an iron ore consisting of a mixture of hydrated iron (III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO (OH)· n H 2 O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, ...
What is the specific gravity of limonite?
Limonite is relatively dense with a specific gravity varying from 2.7 to 4.3. It varies in color from a bright lemony yellow to a drab greyish brown. The streak of limonite on an unglazed porcelain plate is always brownish, a character which distinguishes it from hematite with a red streak, or from magnetite with a black streak. The hardness is variable, but generally in the 4 - 5.5 range.
What is the mineral that makes limonite?
Limonite usually forms from the hydration of hematite and magnetite, from the oxidation and hydration of iron rich sulfide minerals, and chemical weathering of other iron rich minerals such as olivine, pyroxene, amphibole, and biotite. It is often the major iron component in lateritic soils. It is often deposited in run-off streams ...
What was the first use of limonite?
One of the first uses was as a pigment. The yellow form produced yellow ochre for which Cyprus was famous, while the darker forms produced more earthy tones. Roasting the limonite changed it partially to hematite, producing red ochres, burnt umbers and siennas.
Is limonite a hydroxide?
The generic formula is frequently written as FeO (OH)· n H 2 O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 2500 BCE.
Is limonite a mixture?
Although originally defined as a single mineral, limonite is now recognized as a mixture of related hydrated ir on oxide minerals, among them goethite, akaganeite, lepidocrocite, and jarosite.
What is Limonite?
Before modern mineral analysis, the name " limonite " was given to many of the yellowish to yellowish brown iron oxides produced during the weathering of iron-bearing rocks or deposited as bog, lake, and shallow marine sediments.
Where does limonite form?
Limonite often forms as a precipitate at springs and mine openings where acidic, iron-laden waters emerge from the subsurface. Most subsurface waters contain very little oxygen, and when they discharge to the surface, they often encounter oxygenated waters.
What was the first use of limonite?
Their first use of limonite was probably as a pigment. It is found in many Neolithic pictographs, and throughout history it has been one of the most important pigments for creating paints in the yellow to brown color range known as ocher. Its use as a pigment continues today.
Why is limonite mixed with oil?
They are mixed with oil to produce a pigment of the desired consistency and mixed with one another, or other pigments, to produce an infinite number of other hues. Limonite has been used as a low-quality iron ore for thousands of years.
What is a pseudomorph of limonite?
Limonite pseudomorph: A pseudomorph of limonite after pyrite that preserves the original cubic form of the pyrite with its striations. Limonite often replaces pyrite crystals and other materials. This specimen is approximately 4.2 x 3.5 x 3.3 centimeters. Specimen and photo by Arkenstone / www.iRocks.com. ADVERTISEMENT.
Why is the word "limonite" used today?
Today the word "limonite" is used as a field and classroom term for these materials because they cannot be identified in hand specimens and their identity is unknown without laboratory testing.
Does limonite cleave?
Physical Properties of Limonite. Does not cleave because it has an amorphous structure. Limonite staining laterite soil: A profile of laterite soil heavily stained by limonite from Parque Nacional la Mensura, Cuba. USGS photo by Paul Golightly. Limonite: Limonite from Newport, New York.
What is limonite a group name for?
Limonite is actually a group name for the hydrated ferric oxide minerals ( Fe2O3H2O), which occur so commonly in many types of rocks.
Where does Limonite come from?
Limonite constitutes a substantial portion of the heavy minerals in the pre-Quaternary deposits within the Toruń-Eberswalde IMV; it probably comes from eroded terrestrial Miocene deposits and from weathered Pleistocene sediments ( Weckwerth and Pisarska-Jamroży, 2015; see also Pisarska-Jamroży and Zieliński, 2011) eroded from the valley walls. Part, however, should be ascribed to intensive and long-lasting weathering.
What happens to maghemite when heated?
On further heating, at around 400°C, the maghemite will invert to hematite. Therefore, on heating samples containing lepidocrocite, the possible magnetic effects can be strange in that an initially nonmagnetic mineral first inverts to a strong magnetic mineral and finally to a weak magnetic mineral.
What influenced the heavy mineral composition of the sediments?
The erosion by the Scandinavian ice cap and the sub-, supra-, and proglacial meltwater flow conditions influenced the heavy-mineral composition of the sediments. Small differences in the proportions of some mineral species, particularly limonite and glauconite, between the sandurs and the Toruń-Eberswalde IMV might be ascribed to the presence of previously eroded Miocene and Pleistocene material from the IMV substratum.
Overview
Characteristics
Limonite is relatively dense with a specific gravity varying from 2.7 to 4.3. It is usually medium to dark yellowish brown in color. The streak of limonite on an unglazed porcelain plate is always yellowish brown, a character which distinguishes it from hematite with a red streak, or from magnetite with a black streak. The hardness is quite variable, ranging from 1 to 5. In thin section it app…
Names
Limonite is named for the Greek word λειμών (/leː.mɔ̌ːn/), meaning "wet meadow", or λίμνη (/lím.nɛː/), meaning “marshy lake” as an allusion to its occurrence as bog iron ore in meadows and marshes. In its brown form it is sometimes called brown hematite or brown iron ore.
Formation
Limonite usually forms from the hydration of hematite and magnetite, from the oxidation and hydration of iron rich sulfide minerals, and chemical weathering of other iron rich minerals such as olivine, pyroxene, amphibole, and biotite. It is often the major iron component in lateritic soils, and limonite laterite ores are a source of nickel and potentially cobalt and other valuable metals, present as trace elements. It is often deposited in run-off streams from mining operations.
Uses
Nickel-rich limonite ores represent the largest reserves of nickel. Such minerals are classified as lateritic nickel ore deposits.
One of the first uses was as a pigment. The yellow form produced yellow ochre for which Cyprus was famous, while the darker forms produced more earthy tones. Roasting the limonite changed it partially to hematite, producing red oc…
History
While the first iron ore was likely meteoric iron, and hematite was far easier to smelt, in Africa, where the first evidence of iron metallurgy occurs, limonite is the most prevalent iron ore. Before smelting, as the ore was heated and the water driven off, more and more of the limonite was converted to hematite. The ore was then pounded as it was heated above 1250 °C, at which temperature the metallic iron begins sticking together and non-metallic impurities are thrown of…
See also
• Ore genesis
External links
• Mineral galleries
• Mindat
• Gold and limonite
Nomenclature
Composition
- Researchers who studied \"limonite\" discovered that it is amorphous and has a variable composition. It often contains significant amounts of iron oxide minerals such as goethite and hematite. This research revealed that the material called \"limonite\" does not meet the definition of a mineral. Instead, limonite is a mineraloid composed mainly of hydrous iron oxides that are o…
Naming
- Today the word \"limonite\" is used as a field and classroom term for these materials because they cannot be identified in hand specimens and their identity is unknown without laboratory testing. The time and expense required to do this testing is generally not needed, unless the material is going to be used in industry or it is the subject of a detailed study. Thus the name \"li…
Habitat
- Some limonite is found in stratified deposits where hydrous iron oxides form as precipitated sediment on the floor of shallow swamps, lakes, and marine environments. These can be of inorganic or biogenic origin.
Formation
- Limonite often forms as a precipitate at springs and mine openings where acidic, iron-laden waters emerge from the subsurface. Most subsurface waters contain very little oxygen, and when they discharge to the surface, they often encounter oxygenated waters. Dissolved metals in the groundwater rapidly combine with the dissolved oxygen of the surface...
History
- Limonite has been used by people since prehistoric times. Their first use of limonite was probably as a pigment. It is found in many Neolithic pictographs, and throughout history it has been one of the most important pigments for creating paints in the yellow to brown color range known as ocher. Its use as a pigment continues today. It can sometimes be used directly from the deposit …
Uses
- Limonite has been used as a low-quality iron ore for thousands of years. Commercial mining of limonite as a source of iron is no longer done in areas where reasonable deposits of hematite and magnetite are present or readily imported. Limonite deposits are usually too small and too impure for use in modern metallurgy.
Names
- Names such as \"brown iron,\" \"brown hematite,\" \"bog iron,\" and \"brown ocher\" have been used by miners to relate limonite with its potential uses. Their use has declined significantly, and the name \"limonite\" is now used for these various materials.