Hornblende

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Hornblende -among the first to fall!


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It is commonly found in continental rocks which are igneous in origin. It often makes up the dark part of rocks which are composed of light and dark crystals.
Hornblende has been used to estimate the depth of crystallization of plutonic rocks. Those with low aluminum content are associated with shallow depths of crystallization, while those with higher aluminum content are associated with greater depths of crystallization.
Pretty big crystals because of high melting point so separate early and have long time to grow.
hornblende 
Scientific explanation:
Hornblende  (Ca,Na)2–3(Mg,Fe,Al)5(Al,Si)8O22(OH,F)2
is a common constituent of many igneous and metamorphic rocks such as granite, syenite, diorite, gabbro, basalt, andesite, gneiss, and schist. It is the principal mineral of amphibolites. Very dark brown to black hornblendes that contain titanium are ordinarily called basaltic hornblende, from the fact that they are usually a constituent of basalt and related rocks. Hornblende alters easily to chlorite and epidote.