Table of Contents
- 1 What is hornblende?
- 2 What elements are in hornblende?
- 3 What mineral group is hornblende in?
- 4 How do you identify hornblende?
- 5 Why is hornblende called hornblende?
- 6 How do you identify hornblende in a thin section?
- 7 What are the optical properties of hornblende?
- 8 What is the twinning of hornblende?
- 9 What does the name hornblende mean in science?
- 10 What is the composition of the hornblende group?
What is hornblende?
hornblende. / (ˈhɔːnˌblɛnd) / noun. a black or greenish-black mineral of the amphibole group, found in igneous and metamorphic rocks. Composition: calcium magnesium iron sodium aluminium aluminosilicate.
What elements are in hornblende?
Complex basic silicate of sodium, calcium, magnesium, and aluminum. Some members have potassium, titanium, and fluoride. Color, crystal aggregates, and cleavage angle of amphibles. Hornblende is a major rock-forming mineral found in many different types of metamorphic and igneous environments.
What is the chemical formula of amphibole?
Physical Properties for Hornblende
| Chemical Classification | Silicate |
|---|---|
| Diagnostic Properties | Cleavage, color, elongate habit |
| Chemical Composition | (Ca,Na)2–3(Mg,Fe,Al)5(Al,Si)8O22(OH,F)2 |
| Crystal System | Monoclinic |
| Uses | Very little industrial use |
What mineral group is hornblende in?
amphibole group
Hornblende is a member of the amphibole group of more complex silicates, in which the tetrahedra are linked to form a continuous chain twice the width of the pyroxene chains. For this reason they are often referred to as double chain silicates.
How do you identify hornblende?
Identification of Hornblende Hornblende minerals as a group are relatively easy to identify. The diagnostic properties are their dark color (usually black) and two directions of excellent cleavage that intersect at 124 and 56 degrees.
Where can you find hornblende?
Hornblende is a very common mineral found in many geologic environments. It is found in many intrusive igneous rocks ranging in composition from granites to diorite to gabbros to syenites. It occurs as phenocrysts in several varieties of extrusive igneous rocks, such an andesite.
Why is hornblende called hornblende?
The word hornblende is derived from German Horn (‘horn’) and blende (‘deceive’), in allusion to its similar appearance to metal-bearing ore minerals.
How do you identify hornblende in a thin section?
In PPL a thin section of Hornblende ranges from yellow -green to dark brown. Green varieties usually have X= light yellow green, Y=green or grey-green and Z=dark green. Brownish varieties have X=greenish-yelow/brown, Y=yellowish to reddish brown and Z=grey to dark brown.
Where do you find hornblende?
What are the optical properties of hornblende?
Hornblende
| Physical Properties | |
|---|---|
| Transparency | Translucent |
| Streak | White |
| Optical Properties | |
| PPL | Brown, green, blue-green, or yellow-brown Moderate to strong pleochroism “60/120” cleavage (actually 54° and 124°) |
What is the twinning of hornblende?
Simple twinning is relatively common. Crystal habit and cleavage distinguish hornblende from dark-colored pyroxenes. Is a common mineral occuring in both igneous and metamorphic rocks. It characteristically forms near other amphiboles due to the complete solid solution.
What is the formula for the mineral hornblende?
Hornblende is a complex inosilicate series of minerals (ferrohornblende – magnesiohornblende). It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. The general formula is (Ca,Na) 2-3(Mg,Fe,Al)
What does the name hornblende mean in science?
It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende is an isomorphous mixture of three molecules; a calcium-iron-magnesium silicate, an aluminium-iron-magnesium silicate, and an iron-magnesium silicate.
What is the composition of the hornblende group?
A generalized composition for the hornblende group is shown below. (Ca,Na) 2-3 (Mg,Fe,Al) 5 (Si,Al) 8 O 22 (OH,F) 2 Note that calcium, sodium, magnesium, iron, aluminum, silicon, fluorine and hydroxyl can all vary in abundance. This creates a huge number of compositional variants.
How big is a hornblende crystal in length?
A complex inosilicate series of minerals. Hornblende. Hornblende crystal (dark green) about 35 mm long, with apatite (white) General. Category. Silicate mineral. Formula. (repeating unit)