Bobierrite

bobierrite

collinsite

struvite

hannayite

Images

Formula: Mg3(PO4)2·8H2O
Hydrated normal phosphate, vivianite group, paramorph of barićite (both minerals are monoclinic)
Specific gravity: 2.195
Hardness: 2 to 2½
Streak: White
Colour: Colourless to grey-white, colourless in transmitted light
Solubility: Readily soluble in acids
Environments

Pegmatites
Cave deposits

Bobierrite occurs in guano deposits, in phosphatic fossils and as late stage phosphate mineralisation in granite pegmatites (Mindat). Associated minerals include hannayite, schertelite, lithiophilite, sicklerite, purpurite, collinsite, apatite, dolomite and calcite (HOM, Mindat).

Localities

At Wodgina, Abydos Station, Port Hedland Shire, Western Australia, bobierrite occurs as a rare alteration product of primary phosphate-bearing minerals in pegmatites (HOM).

At the type locality, the Mejillones peninsula, Antofagasta Province, Chile, bobierrite is formed from the chemical alteration of a guano deposit, associated with schertelite and hannayite (Mindat).

At the Imperial Canyon Lava tubes, Chyulu Hills, Makueni county, Kenya, bobierrite is formed from the chemical alteration of a guano deposit (HOM).

At the Bendada pegmatite, Sabugal, Guarda, Portugal, bobierrite occurs as a rare alteration product of primary phosphate-bearing minerals (HOM).

At Edgerton, Minnesota, USA, bobierrite was formed from the chemical alteration of a fossilised elephant tusk (HOM).

Alteration

Mixtures of the commonly associated minerals hannayite, schertelite, bobierrite, newberyite and struvite may be formed by reaction of magnesium with concentrated ammonium phosphate solutions of the guano deposit, followed by alterations in the course of leaching and aeration. In water, struvite alters slowly to cattiite and then to the more stable bobierrite (AM 48.635-641).

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