884 General Notes. [September, 
of the forest are not older than Roman times, the clays in which 
the forest is rooted are either coéval with or younger than the 
bronze age in Britain.” In December, 1883, the sea tore away 
the beach so as to expose this clay, at the junction of which with 
the Trias were found hearths of trap rock with bits of pottery, 
grindstones, glass, tin, slag and ingots of copper, leading to the 
conclusion that tin was smelted and bronze made prior to the 
deposition of the forest clay upon the surface of the Trias rock. 
Submergence need not be predicated, the damming back of the 
sea and the growth of trees below high-water mark behind the 
- damı furnish a probable explanation of the phenomena. 
MINERALOGY AND PETROGRAPHY.' 
AMPHIBOLE-ANTHOPHYLLITE FROM Mr. WASHINGTON, BALTI- 
MORE COUNTY.—A light-gray or brownish colored mineral, with a 
bronzy luster, occurs in considerable quantity as a gangue of the 
chalcopyrite ore which is mined a short distance north-west of the 
village of Mt. Washington, Baltimore county, Md. It is most 
frequently found in thin blade-like individuals varying much in 
size and with only faint indications of crystal planes. Such 
During the past fall blades of unusual size (10™ X 2°) were 
found, which had the planes æ Pz and æ P of the prismatic zone 
well developed. The angle between the planes of the prism 
(124° 30’) placed the hornblendic nature of the mineral beyon 
a doubt. The great purity and transparency of some of the 
material seemed to invite a chemital and optical examination 
which was accordingly undertaken by Mr. C. S. Palmer, of the 
_ chemical laboratory of the Johns Hopkins University. Some 
specimens of a reddish-brown color were translucent—almost 
transparent—though 2™™ in thickness. In these the usual fibrous 
structure parallel to the vertical axis was hardly noticeable, but 
a parting parallel to a very flat clinodome was quite pronounced, 
A chemical analysis of this freshest and most homogeneous 
material gave the following results : 
SiO, Al,0, FeO, FeO CaO MgO NaO K,O _ total 
$7.28 .,0.75 1.73 5.64 tr. 21.70 2.80 99 
This will be at once recognized as the composition of a typical 
=~ anthophyllite. The specific gravity is 3.068. No pleochroism 
= is visible in thin sections, but in transparent crystals of consid- 
~ erable thickness a decided difference both in the color and inten- 
sity of the rays is observable. The one vibrating parallel to c is 
a light copper-red, while that parallel to b is yellow. Absorp- 
Edited by Dr. Gro, H. Witt1ams, of the Johns Hopkins University, Baltimore. 
