Question: What is the name for the lava, often found with Pele's tears, defined as volcanic glass fibers or thin strands of volcanic glass?
Context: Pozzolana, also known as pozzolanic ash ("pulvis puteolanus" in Latin), is a siliceous or siliceous and aluminous material which reacts with calcium hydroxide in the presence of water at room temperature (cf. pozzolanic reaction).  In this reaction insoluble calcium silicate hydrate and calcium aluminate hydrate compounds are formed possessing cementitious properties.  The designation pozzolana is derived from one of the primary deposits of volcanic ash used by the Romans in Italy, at Pozzuoli.  Nowadays the definition of pozzolana encompasses any volcanic material (pumice or volcanic ash), predominantly composed of fine volcanic glass, that is used as a pozzolan.  Note the difference with the term pozzolan, which exerts no bearing on the specific origin of the material, as opposed to pozzolana, which can only be used for pozzolans of volcanic origin, primarily composed of volcanic glass. Volcanic glass is the amorphous (uncrystallized) product of rapidly cooling magma.  Like all types of glass, it is a state of matter intermediate between the close-packed, highly ordered array of a crystal and the highly disordered array of gas.  Volcanic glass can refer to the interstitial, or matrix, material in an aphanitic (fine grained) volcanic rock or can refer to any of several types of vitreous igneous rocks. Most commonly, it refers to obsidian, a rhyolitic glass with high silica content. Aphanite, or aphanitic as an adjective (from the Greek αφανης, "invisible"), is a name given to certain igneous rocks that are so fine-grained that their component mineral crystals are not detectable by the unaided eye (as opposed to phaneritic igneous rocks, where the minerals are visible to the unaided eye).  This geological texture results from rapid cooling in volcanic or hypabyssal (shallow subsurface) environments.  As a rule, the texture of these rocks is not the same as that of volcanic glass (e.g., obsidian), with volcanic glass being non-crystalline (amorphous), and having a glass-like appearance. Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter.  The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as tephra), including particles larger than 2mm.  Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere.  The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass.  Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma.  Once in the air, ash is transported by wind up to thousands of kilometers away. Limu o Pele or Pele's seaweed (Hawaiian, literally, "seaweed of Pele", after Pele the Hawaiian fire goddess of volcanoes) is a geological term for thin sheets and subsequently shattered flakes of brownish-green to near-colourless volcanic glass lava spatter that commonly resemble seaweed in appearance, that have been erupted from a volcano.  Limu o Pele is formed when water is forced into and trapped inside lava, as when waves wash over the top of the exposed flows of the molten rock.  The water boils and is instantly converted to steam, expanding to form bubbles within the lava.  The lava rapidly cools and solidifies as the bubbles grow.  The volcanic glass bubbles burst and are dispersed by the wind, showering flakes of glass downwind. Palagonite is an alteration product from the interaction of water with volcanic glass of chemical composition similar to basalt.  Palagonite can also result from the interaction between water and basalt melt.  The water flashes to steam on contact with the hot lava and the small fragments of lava react with the steam to form the light colored palagonite tuff cones common in areas of basaltic eruptions in contact with water.  An example is found in the pyroclastic cones of the Galapagos Islands.  Charles Darwin recognized the origin of these cones during his visit to the islands.  Palagonite can also be formed by a slower weathering of lava into palagonite, resulting in a thin, yellow-orange rind on the surface of the rock.  The process of conversion of lava to palagonite is called "palagonitization." Pele’s tears is a geological term for small pieces of solidified lava drops formed when airborne particles of molten material fuse into tearlike drops of volcanic glass.  Pele’s tears are jet black in color and are often found on one end of a strand of Pele's hair.  Pele's tears is primarily a scientific term used by volcanologists. Pele's hair is a form of lava.  It is named after Pele, the Hawaiian goddess of volcanoes.  It can be defined as volcanic glass fibers or thin strands of volcanic glass.  The strands are formed through the stretching of molten basaltic glass from lava, usually from lava fountains, lava cascades, and vigorous lava flows. Pitchstone is a dull black glassy volcanic rock formed when a felsic viscous lava or magma cools quickly.  It is similar to obsidian but is defined by the International Union of Geological Sciences as having a higher water content.  It is a volcanic glass; however, unlike a glass, pitchstone has an irregular hackly fracture not a conchoidal fracture.  That is due to its coarser (than obsidian) crystal structure.  Pitchstone has a resinous lustre, or silky in some cases, and a variable composition.  Its colour may be mottled, streaked, or uniform brown, red, green, gray, or black.  It is an extrusive rock that is very resistant to erosion. Hyalopilitic is a textural term used in petrographic classification of volcanic rocks. Specifically, hyalopilitic refers to a volcanic rock groundmass, which is visible only under magnification with a petrographic microscope, that contains a mixture of very fine-grained mineral crystals either mixed with natural volcanic glass, or surrounded by thin bands of volcanic glass.
Answer: Pele's hair