serpentine

views updated May 08 2018

serpentine A group of minerals belonging to the 1:1 group of phyllosilicates (sheet silicates) with the composition Mg6 [Si4O10](OH)8 and including the minerals chrysotile (the asbestiform variety), lizardite, and antigorite; sp. gr. 2.55–2.60; *hardness 2.0–3.5; monoclinic; chrysotile is fibrous whereas lizardite and antigorite occur as flat tabular crystals or massive; various shades of green, also brown, greywhite, or yellow; greasy to waxy lustre, occasionally silky; formed from altered olivine and orthopyroxene. It results from the alteration of ultramafic (see ULTRABASIC) rocks either by hydrothermal action at a late stage or by alteration during metamorphism, chrysotile forming first and then altering to antigorite; it is a constituent of ophicalcites, a serpentine-calcite rock derived from the dedolomitization (see DEDOLOMITE) of a siliceous dolomite. It is used extensively as a facing stone and for ornament; chrysotile has been used as a source of commercial asbestos in Thetford, Canada. Lizardite occurs on the Lizard Peninsula, Cornwall, UK.

serpentine

views updated May 21 2018

ser·pen·tine / ˈsərpənˌtēn; -ˌtīn/ • adj. of or like a serpent or snake: serpentine coils. ∎  winding and twisting like a snake: serpentine country lanes. ∎  complex, cunning, or treacherous: his charm was too subtle and serpentine for me.• n. 1. a dark green mineral consisting of hydrated magnesium silicate, sometimes mottled or spotted like a snake's skin.2. a thing in the shape of a winding curve or line, in particular: ∎  a riding exercise consisting of a series of half-circles made alternately to right and left.3. hist. a kind of cannon, used esp. in the 15th and 16th centuries.• v. [intr.] move or lie in a winding path or line: fresh tire tracks serpentined back toward the hopper.

serpentine

views updated May 29 2018

serpentine Group of sheet silicate minerals, hydrated magnesium silicate (Mg3Si2O5(OH)4). Serpentine minerals come in various colours, usually green, although sometimes brownish, with a pattern of green mottling. They have monoclinic system crystals. They are commonly used in decorative carving; fibrous varieties are used in asbestos cloth. Hardness 2.5–4; r.d. 2.5–2.6.