Properties of Hornblende

Hornblende is a group of dark-colored, ferrous-iron-rich amphibole minerals. It is a complex inosilicate series with a wide range of chemical compositions, but it is typically characterized by the presence of calcium, magnesium, iron, and aluminum.

Image of hornblende mineral
Credit: James St. John, CC BY 2.0, via Wikimedia Commons

The following table provides a comprehensive list of hornblende properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).

Note: click on the icon to switch between Metric and Imperial units.

Table of Hornblende Properties
Physical Properties
Metric
Chemical FormulaCa2(Mg,Fe)4Al(Si7AlO22)(OH)2
Crystal SystemMonoclinic
Mohs Hardness5 - 6
Density3000 - 3400 kg/m3
ColorBlack to dark green or brown
LusterVitreous to dull
FractureUneven
StreakPale gray, gray-white, white, colorless

Note: unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)

Related Pages
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017.