Abstract

Introduction

Tourmaline is a not uncommon mineral in the northern part of Jefferson county, Colorado. It is to be found as an ingredient of the quartz-feldspar boulders which strew the mesas bordering the foothills west of Denver and in the beds of the streams which drain the crystalline schists of these foothills. It may also be found in place in the numerous pegmatite veins that everywhere cut the schists. Beautiful lustrous black crystals, often two or more inches in diameter, have been obtained from these pegmatite veins. In rare cases colors other than black may be seen, as for instance, some small crystals, about a quarter of an inch in diameter, with white centers and black margins, found in a pegmatite boulder near Golden.

While the pegmatite veins may well be considered the habitat of the Jefferson County tourmalines, in some cases this mineral occurs with somewhat different association. On . . .

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