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also tach·y·lite  (tăk′ə-līt′)
A brown, black, or green volcanic glass formed from basaltic magma and often found along the edges of dikes, sills or volcanic flows, where rock usually forms first by contact with the cooler surrounding rock.

[German Tachylyt : Greek takhu-, tachy- + Greek lutos, soluble (from lūein, to loosen; see leu- in Indo-European roots).]

tach′y·lyt′ic (-lĭt′ĭk) adj.


(ˈtækɪˌlaɪt) or


(Geological Science) a black basaltic glass often found on the edges of intrusions of basalt
[C19: from German Tachylit, from tachy- + Greek lutos soluble, melting, from luein to release; so called because it fuses easily when heated. The form tachylite is influenced by -lite stone]
tachylytic, ˌtachyˈlitic adj
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References in periodicals archive ?
Overall, ash grains were separated with the micro stereoscope and classified into: visibly altered lithic fragments, visibly altered free crystals, dark tachylitic scoria, translucent sideromelane, and unaltered free crystals.
Figure 3E is an optical image of an altered tachylitic scoria with oxidation of mafic components of the glass, particularly in the inner surfaces of the vesicles.
The tachylitic scoria (Fig 4A) appear unaltered and have a porphyritic texture with occasional phenocrysts of unaltered plagioclase imbedded in a black, vitreous matrix.
Grain A5 is a tachylitic scoria from the March 12, 2015 eruption collected near the active crater.
7 [phi] fraction of the ashes are: altered sideromelane, altered tachylitic scoria, hydrothermally altered lithics, altered plagioclase crystals, sulphur and gypsum crystals.
Rare monocrystalline sand grains of clinopyroxene are also present, as are microlitic lithic fragments (plagioclase microlites set in nearly opaque tachylitic glass) probably derived from chilled lava surfaces or basaltic tephra.