"ACTINQLITE: _Calcium-magnesium-iron, Amphibole_,

Ca (Mg Fe)_{3}(Si O{4}){3}.

Specific Gravity, 3-3.2. Hardness, 5-6. Streak, uncolored.... Fine
radiated olive-green crystals are found ... at Taylorstown...."

"TREMOLITE: _A variety of Amphibole. Calcium._

_Magnesium Amphibole._ Ca Mg{2}(Si O{4}){3}.

Specific Gravity, 2.9-3.1. Hardness, 5.6. Long bladed crystals; also
columnar and fibrous. Color, white and grayish. Sometimes nearly
transparent. Found in the greenish talcose rocks at Taylorstown."

_Chromite_, of which no occurrence of economic importance has yet been
discovered in the County or elsewhere in Virginia.

"[9]On the eastern flank of the Catoctin rests a thin belt of mica
slate. This rock is composed of quartz and mica in varying
proportions, and this belt, on reaching the Bull Run Mountain, there
expands itself, and forms the whole base of that mountain, and where
the mica predominates, as it does there, it sometimes forms excellent
flagging stones."

[Footnote 9: Taylor's _Memoir_.]

* * * * *

"Immediately at the western base of the Catoctin Mountain, a range of