R1825: Diorite. Near Azusa, Los Angeles County, California

Title: R1825: Diorite. Near Azusa, Los Angeles County, California
Description: MACROSCOPIC: A dark gray medium grained somewhat gneissoid rock consisting of black hornblende, glassy plagioclase, with occasional yellow brown grains of sphere/
MICROSCOPIC: Green hornblende, the dominant species contributes to a moderately well-developed gneissoid foliation in subparallel subhedra, partly replated by biotite, in both anhedral patches and euhedral tablets. The medium plagioclasae in anhedral, slightly zoned gradationally and locally has central parts sericitized. Large sphene euhedra form a conspicuous accessory. Other are epidote, rare allanite, apatite and magnetite.
Source: Wards Collection of North American Rocks
Contributor: Hana Isihara
Identifier: R1824
Mediator: Tamara Carley (carleyt@lafayette.edu)
Rights Holder: Lafayette College Department of Geology and Environmental Geosciences

Media: https://exhibits.lafayette.edu/geology/files/original/78bb55371b1f67b31d371d2754a8c7c4.jpeg; https://exhibits.lafayette.edu/geology/files/original/385c8db52d7f4f352997d8d673a8b116.jpeg; https://exhibits.lafayette.edu/geology/files/original/e71041806e342109c608b95ea0924e67.jpeg; https://exhibits.lafayette.edu/geology/files/original/870f5085d44cf17f76533cd32f337fd8.jpeg; https://exhibits.lafayette.edu/geology/files/original/4aa0d5e69fd3e70732a29660a1a0e52a.jpeg; https://exhibits.lafayette.edu/geology/files/original/36af87c45eab5c2cf90683c2bbeb6ce7.jpeg; https://exhibits.lafayette.edu/geology/files/original/fef95df07a73d3f4de93d1d62ae81889.jpeg; https://exhibits.lafayette.edu/geology/files/original/d8bc544242d0163441e6f3dd98ca0a1f.jpeg