Phosphate of Iron
- Phosphate of Iron. Thompson. 4. 481. Cadet, Journ. de Physique. 58. 259. Fourcroy, Ann. de Chimie. 50. 200.
- Blue Iron Earth. Native Prussian Blue. Thompson 4. 482.
- Fer Azuré. Haüy 4. 119.
- Blue Martial Earth. Kirw. 2. 185.
- Blau Eisenerde. Emmerl. 2. 359.
“Phosphate of Iron is found in considerable quantities near the Black Sea, accompanied by animal remains; Pallas discovered a specimen exhibiting a radiated crystallization of the pure phosphate, which he believed to be blue selenite, it has also been supposed to be hornblende of this unique appearance. The Rev. J. Holme, of Cambridge, ascertained the combination of the Phosphoric acid with iron in this mineral.” Dr. Clarke.
It has been found native in the Brazils and the Isle of France, and is said to have been first detected by Vauquelin. Specimens brouglit by Mr. Roch from the Isle of France were subjected to chemfcal analysis by Cadet and Laugier*.
The powdery blue phosphate is extremely common in two varieties, as I have shown in Tab. II, British Mineralogy.
The radiated and crystallized form is certainly rare at present among Mineralogists; I know of no other specimen in England than this, which is lent me by Dr. Clarke of Cambridge, well known for his foreign researches, and attention to Mineralogy.
The radii are longitudinally laminated, the laminæ; parallel to four-sided prisms of about 122° and 58°. The cros fracture splintery and shining. Sometimes we find a truncation at one or more edges of the prism. On the specimen the radii look opaque shining black, but when separated, if viewed through the broader face of the prisms, they appear nearly colourless, if through the narrower one, light brown, and in the directon of the diagonal, of a deep blue. Spec. Grav. according to Cadet 2.539, according to Laugier 2.6.
|Analysis by Cadet.||By Laugier.|
|Oxide of Iron||41.25||42.1|
- * Thompson v. 4. p. 481.