Editing Hornblende (section)

== Physical properties ==
Hornblende has a [[Mohs scale of mineral hardness|hardness]] of 5–6, a [[specific gravity]] of 3.0 to 3.6, and is typically an opaque green, dark green, brown, or black color. It tends to form slender prismatic to bladed crystals, diamond-shaped in cross section, or is present as irregular grains or fibrous masses.<ref name=Nesse2000>{{cite book |last1=Nesse |first1=William D. |title=Introduction to mineralogy |date=2000 |publisher=Oxford University Press |location=New York |isbn=9780195106916 |pages=285–286}}</ref>

Its planes of [[cleavage (crystal)|cleavage]] intersect at 56° and 124° angles. Hornblende is most often confused with the [[pyroxene]] series and [[biotite|biotite mica]], which are also dark minerals found in [[granite]] and [[charnockite]]. Pyroxenes differ in their cleavage planes, which intersect at 87° and 93°.<ref>{{cite book |title=A Field Guide To Rocks and Minerals |last=Pough |first=Frederick H. |publisher=Houghton Mifflin |location=Boston |year=1976 |edition=4 |page=249}}</ref>

Hornblende is an inosilicate (chain silicate) mineral, built around double chains of silica tetrahedra. These chains extend the length of the crystal and are bonded to their neighbors by additional metal ions to form the complete crystal structure.{{sfn|Nesse|2000 |p=277–279}}