Hydrocides, halides and phoshates

Kva er hydroxides?

* common, produced by wearhering and hydration of other minerals
* occur as fine-graind aggregates, usually mixed with other minerals

brucite Mg(OH)2 vs gibersite Al(OH)3 structure

Sei litt om brucite

* Mg(OH)2
* trigonal
* hexagonal mica-like plates, often aggregates
* H=2.5
* p=2.39 g/cm^3
* colorless in thin sections
* n=1.559-1.600 (low relief)

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Sei litt om Gibbsite

* Al(OH)
* monoclinic
* appears in soils, product of weathering of feldspars, major mineral in bauxite together with bömite and diaspore

Sei litt om limonite

* iron hydoxide minerals
* it is a collectiv term used for mixtures of various Fe oxide and hydroxide minerals- most commonly:
* goethite - alfa-FeO(OH)
* lepifocrocite- y-FeO(OH)
* hematite (Fe2O3)
* intens weathering of Fe-bearing rocks may result in formation of lateritic soils rich in iron hydroxides- deposits of Fe ore
* yellowish brown or redish stain in weathering rocks is very-finegraind goethite, lepidocrocite hematite+ other minerals

Sei litt om haldies

In halides, the anion is one of the halgeon elements F,Cl, Br and I. Their structure is made by ionic bonds of the halogens with other cations. Halides are highly soluble in H2O

Sei litt om Halite og sylvite

halite-NaCl, sylvite-KCl

* isometric symmetry
* crysrals are cubes with perfect (100) cleavage
* both minerals are isostructural with Na^+ or K^+ cations present in octahedrally coordinated sites surrounded by 6 Cl^- anions
* use: dietart purposes, manufacturing of industrial chemicals, metal processong, pharmaceutical industry, paper production. sylvite is used for as a source of potassium in fertilizer

Sei litt om Fluorite

CaF2

* isometric symmetry
* colourless, blue, purple, green, yellowish…colours
* crystals are cubes with perfect (111) cleavage
* in fluorite,Ca^2+ cations are present in 8-fold coordinated sites (surrounded by 8F^- anions)
* use: principal source of F for chemical processes. it is also used as melting agent (flux) in steel production

Sei litt om Gypsum

(CaSO4x2H2O)- monoclinic symmetry

* with, pale gray, brown, yellow…
* crystals are mostly tabular parallel to (010)
* common twinning along (100) plane
* large euhedral crystals are called selenite
* granular massive gypsum is called alabaster

Sei litt om anhydrite

CaSO4

* orthorombic symmetry
* colourless, with, gray, bluish..
* crystals are blocky or tabular, often just massiv
* gypsum: H=2
* anhydrite: H=3-3.5
* use: anhydrite is mixed with portland cement to control the rate of curing (hardening). when prepared in lab, CaSO4 is used as carrier for antiviotics and in some other medical applications

Sei litt om barite

BaSO4

* orthorombic symmetry
* withe, pale yellow, gray, pale green…
* crystals are tabulare parallel to (001), often intergrown to form rosettes or just granulart masses
* H=2.5-3.5
* p=4.5 g/cm^3
* use: most barite is mined as industria, mineral in order to use its high specific gravity. it is used in the petroleum industry as a componet of drillling mud in oil and gas wells. glassmaking, ceramics, high-density filler in plastcs and rubber

Sei litt om apatite

Ca5(PO4)3(OH,F,Cl)

* hexagonal symmetry
* grayish blue-green, geen, yellow..
* colourless in thin section
* crystals are hexagonal prismatic
* n=1.629-1.666 (medium relief)
* d= 0.001-0.007 (gray interf. col.)
* OH

Sei litt om Monazite og Xenotime

monazite-(Ce,La,Th)PO4

* monoclinic symmetry
* yellow, reddish yellow or brown
* yellow or colourless in thin sections
* tabular crystals
* n= 1.772-1.860 (high relief)
* d=0.045-0.075 (3rd-4th order)

Xenotime-YPO4

* tetragonal symmetry
* elongate tetragonal prisms

Use in sicence: both concentrate U and are being used for high-temprature (U-Pb) geochronology

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