Ferrous phosphate
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Description
A hygroscopic, blue-gray powder that occurs naturally as the mineral Vivianite. Vivianite was described after discovery in the St. Agnes mine in Cornwall in 1817. It has been called 'blue ocher' and has been found in Roman paint residues. Ferrous phosphate is used as a colorant in ceramics.
Synonyms and Related Terms
iron phosphate; vivianite; blue ochre; blue ocher; ocre de fer (Fr.)
Other Properties
Soluble in mineral acids. Insoluble in water.
Euhedral crystals with strong pleochroism from colorless to lilac blue. Strongly birefringent under crossed polars.
| Composition | Fe3(PO4)2.8H2O |
|---|---|
| CAS | 14940-41-1 |
| Density | 2.58-2.68 |
| Molecular Weight | mol. wt. = 357.48 |
| Refractive Index | 1.60; 1.63; 1.65 |
Hazards and Safety
Slowly decomposes and darkens in light and air.
Comparisons
Characteristics of Common Blue Pigments
Sources Checked for Data in Record
- Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall, Pigment Compendium, Elsevier Butterworth-Heinemann, Oxford, 2004
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- R.D. Harley, Artists' Pigments c. 1600-1835, Butterworth Scientific, London, 1982
- The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 4101
- Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000