Apophyllite

Habit and occurrence
A few specimens of apophyllite were found during the sinking of the Palmer shaft which show rosette-shaped groups and platy single crystals, some of which are half an inch across.

Figure 183
Tabular crystal of apophyllite showing the forms c(001), a(100), and p(111). Palmer shaft.

The apophyllite is implanted upon green epidote lining an irregular cavity in hornblende gneiss. With it are numerous crystals of pyrite, minute distorted crystals of brown garnet, and a very few crystals of pale-brown axinite. The cavity was found in the gneissic footwall rock of the ore body, in which the shaft was sunk, and at a depth of 600 feet on the incline.

Groups of pale-pink crystals, showing only the unit pyramid and the base, implanted on crumbly limestone, were found in the mine at Franklin, on the 300-foot level north. They were the material analyzed.

Composition
Apophyllite is a hydrous silicate of calcium and potassium. Although not strictly a zeolite, as it contains no aluminum, it is generally classed with that group on account of its behavior before the blowpipe.

**Analysis of apophyllite**
	1	2
SiO₂	50.90	0.847	= 3 x 0.282
CaO	24.74	0.441*
ZnO	1.79	0.022*
MnO	0.47	0.007*	0.516 = 2 x 0.238
K₂O	3.70	0.039*
Na₂O	0.42	0.007*
H₂O	17.71	0.984*	= 3.5 x 0.281
	99.73

[* Figures reflected in the value 0.516 shown.]

1. Apophyllite, Franklin. L. H. Bauer (273), analyst.

2. Molecular ratio of no. 1.

From the molecular ratio shown is derived the formula given above, which, although not the formula ordinarily assigned to apophyllite, is of the same general type. It will be noted that. the material analyzed, although undoubtedly apophyllite, differs in composition from the ordinary type of that mineral by appreciable amounts of all the constituents and especially in containing zinc and manganese to the molecular amount of about one-sixteenth of the bivalent bases.


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