Hornblende PPL properties Relief: High positive Habit/Form: Commonly found as slender prismatic to bladed crystals with a diamon-shaped cross section showing the amphibole cleavage at 56° and 124°.

Apr 23, 2023 · 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 …

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.

People trying to identify hornblende in hand sample often find it helpful to look for “sparkly tree bark.” Scanning electron micrograph of a hornblende grain plucked from a garnet-rich sand from the Moray Coast in northeastern Scotland (there’s diatom tests on it!)

Hornblende is the general name used for calcic amphiboles identified only by physical or optical properties. The most common amphibole, hornblende, has very variable composition owing to significant substitution of Na + and K + in A site and Fe 3+ and Al 3+ in M 1-2-3 sites.

Hornblende and plagioclase (with sieve texture) crystals in a Andesite from Equador. PPL image, 2x (Field of view = 7mm) Clinopyroxene, plagioclase and magnetite crystals.

Hornblende is the major mineral of the amphibole group. Its composition is variable and its general formula is (Ca,Mg,Al)Si 8 O 22 (OH) 2 . Its color varies from dark-brown to dark-green, appearing black from a distance (as most mafic minerals).

A hornblendite is an ultramafic igneous rock dominated by hornblende. It is different from an amphibolite which is a amphibole and plagioclase dominated metamorphic rock. Horblendite is a rare rock most commonly associated with diorite, granite, gabbro and peridotite.

Apr 21, 2012 · Optical properties of Minerals under Plane Polarized Light (PPL) The PPL arrangement of the Petrological microscope is with the Analyzer in the "out" position. The optical properties that can be seen under this arrangement are as follows,

Colour in PPL: pale green, green, yellow-brown, brown Pleochroism: moderate to strong Relief: moderate Distinction: hornblende distinguished from actinolite by extinction angle between 10 o and 15 o of later (13 o - 35 o in hornblende) Occurrence: wide range of igneous and metamorphic rocks, with subsequent wide range in chemistry