Phosphate of Lime, or Apatite
- Class 2. Earths.
- Order 1. Homogeneous.
- Gen. 3. Calx.
- Spec. 3. Phosphata.
- Div. 1. Crystallized.
- Gemeiner apatit. Emmerl. 1. 502.
- Chaux phosphorée, Apatite. De Born, 1. 363.
- Calx, combined with Phosphoric Acid. Kirw. 1. 128.
- Amethyste basaltine. De Lisle, 2. 254.
- Chaux phosphatée. Haüy, 2. 234.
Apatite has not long been known as a native substance of Great Britain, and I believe it has only been found at Stenna Gwyn, in Cornwall, from whence I have received it by favour of Mr. Rashleigh. In many instances the crystals are so small and so much imbedded in talcose rock as scarcely to be discernible, and it is not uncommon for the rock itself, or rather the gangue, to be thought Phosphate of Lime altogether. The present specimen was procured some years since, and is still a fine one, particularly as it shows the primitive crystal, and the nature of its fracture, which is very distinctly and neatly apparent. It also shows some of the various tints, such as purplish, blueish and greenish, natural to it, though rather palely*. Apatite is infusible by the blowpipe. Powdered, and thrown on red-hot coals, it emits a yellowish green phosphorescent light. It is soluble in muriatic acid, and the solution becomes gelatinous. No decomposition of the phosphoric acid from the Lime takes place. This plate shows the integrant molecule, a regular triangular prism, very distinct in the fractures of the specimen, and also the primitive hexangular prism. It has been noticed as found in Spain and, Germany by most mineralogists:—In the former it constitutes large mountains.
- * We have since received a fine specimen of an opaque white, and water blue, from Dr. Turton, about a quarter of an inch in length.