mansfieldite
An orthorhombic-dipyramidal mineral containing aluminum, arsenic, hydrogen, and oxygen.

mantienneite
An orthorhombic-dipyramidal yellow brown mineral containing aluminum, hydrogen, magnesium, oxygen, phosphorus, potassium, and titanium.

mapimite
A monoclinic-domatic mineral containing arsenic, hydrogen, iron, oxygen, and zinc.

marblework
artistic work done in marble

marecottite
A triclinic-pinacoidal yellow orange mineral containing hydrogen, magnesium, manganese, oxygen, sulfur, and uranium.

marekanite
An Apache tear (obsidian nodule).
The material which such nodules consist of.

marekanites
plural of marekanite

margaritasite
A yellow monoclinic caesium-bearing mineral in the carnotite group.

margarosanite
A triclinic-pinacoidal mineral containing calcium, lead, manganese, oxygen, and silicon.

marialite
A tetragonal-dipyramidal mineral containing aluminum, chlorine, oxygen, silicon, and sodium.

marialites
plural of marialite

maricite
An orthorhombic-dipyramidal mineral containing iron, oxygen, phosphorus, and sodium.

maricopaite
An orthorhombic-dipyramidal white mineral containing aluminum, calcium, hydrogen, lead, oxygen, and silicon.

marinite
A gray to black oil shale of marine origin in which the chiefmain organic components are lamalginite and bituminite derived from marine phytoplankton, with varied admixtures of bitumen, telalginite and vitrinite

marinites
plural of marinite

markfieldite
Synonym of microdiorite.

markfieldites
plural of markfieldite

marlite
A wind-resistant variety of marl.

marlites
plural of marlite

marmarization
Transformation into marble.

marmarosis
The metamorphosis of limestone into marble.

marmatite
A dark form of sphalerite that is rich in iron

marmatites
plural of marmatite

marmolite
A form of chrysotile

marmoration
A covering, casing or encrusting of marble
a variegated pattern resembling marble; a marbly quality

marmorations
plural of marmoration

marmorization
The metamorphosis of limestone into marble.

marmorizations
plural of marmorization

marmorosis
The metamorphosis of limestone into marble.

marrite
A monoclinic-prismatic mineral containing arsenic, lead, silver, and sulfur.

marshite
An isometric-hextetrahedral mineral containing copper and iodine.

marsturite
A triclinic mineral containing calcium, hydrogen, manganese, oxygen, silicon, and sodium.

marteaux
plural of marteau

marthozite
An orthorhombic-pyramidal mineral containing copper, hydrogen, oxygen, selenium, and uranium.

martite
A variety of hematite that is pseudomorphic after magnetite crystals.

martites
plural of martite

marumoite
A monoclinic-sphenoidal lead gray mineral containing arsenic, lead, and sulfur.

maslovite
An isometric-tetartoidal steel gray mineral containing bismuth, platinum, and tellurium.

masrite
A variety of halotrichite containing manganese and cobalt.

masutomilite
A monoclinic-prismatic purple pink mineral containing aluminum, fluorine, hydrogen, lithium, manganese, oxygen, potassium, and silicon.

mathewrogersite
A trigonal mineral containing aluminum, copper, germanium, hydrogen, iron, lead, oxygen, and silicon.

mathiasite
A trigonal-rhombohedral black mineral containing calcium, chromium, iron, magnesium, oxygen, potassium, strontium, and titanium.

matildite
A trigonal-hexagonal scalenohedral white mineral containing bismuth, silver, and sulfur.

matlockite
A tetragonal-ditetragonal dipyramidal mineral containing chlorine, fluorine, and lead.

matraite
A trigonal-ditrigonal pyramidal brownish yellow mineral containing sulfur and zinc.

mattagamite
An orthorhombic-dipyramidal violet mineral containing cobalt and tellurium.

matteuccite
A monoclinic-domatic colorless mineral containing hydrogen, oxygen, sodium, and sulfur.

mattheddleite
A hexagonal-dipyramidal mineral containing chlorine, lead, oxygen, silicon, and sulfur.

mauleonite
Synonym of leuchtenbergite.

mawbyite
A monoclinic-prismatic mineral containing arsenic, hydrogen, iron, lead, oxygen, and zinc.

mawsonite
A tetragonal-scalenohedral brownish orange mineral containing copper, iron, sulfur, and tin.

maxaxite
Synonym of blue beryl.

maxwellite
A monoclinic dark red mineral containing arsenic, fluorine, iron, oxygen, and sodium.

mayenite
An isometric-hextetrahedral colorless mineral containing aluminum, calcium, and oxygen.

mayingite
An isometric-diploidal steel black mineral containing bismuth, iridium, and tellurium.

mazapilite
Synonym of arseniosiderite.

mazzettiite
An orthorhombic light gray mineral containing antimony, lead, mercury, silver, and tellurium.

mbobomkulite
A monoclinic mineral of the chalcoalumite group.

mcallisterite
A trigonal-hexagonal scalenohedral mineral containing boron, hydrogen, magnesium, and oxygen.

mcalpineite
An isometric mineral containing copper, hydrogen, oxygen, and tellurium.

mcauslanite
A triclinic-pedial mineral containing aluminum, fluorine, hydrogen, iron, oxygen, and phosphorus.

mcbirneyite
A copper-oxygen-vanadium mineral.

mcconnellite
A trigonal-hexagonal scalenohedral dark red mineral containing chromium, copper, and oxygen.

mccrillisite
A mineral comprising mainly cesium, zirconium, phosphorus, and oxygen.

mcgillite
A monoclinic-prismatic mineral containing chlorine, hydrogen, iron, magnesium, manganese, oxygen, and silicon.

mcgovernite
A trigonal-hexagonal scalenohedral mineral containing arsenic, hydrogen, magnesium, manganese, oxygen, silicon, and zinc.

mcguinnessite
A monoclinic-prismatic mineral containing carbon, copper, hydrogen, magnesium, and oxygen.

mckinstryite
An orthorhombic-dipyramidal light grayish white mineral containing copper, silver, and sulfur.

mcnearite
A triclinic white mineral containing arsenic, calcium, hydrogen, oxygen, and sodium.

medaite
A monoclinic-prismatic brownish red mineral containing arsenic, calcium, hydrogen, manganese, oxygen, silicon, and vanadium.

medmontite
A rare, copper-bearing mineral of the montmorillonite group.

megabasite
Synonym of wolframite.

megacyclite
A monoclinic-prismatic mineral containing hydrogen, oxygen, potassium, silicon, and sodium.

megakalsilite
A hexagonal-pyramidal colorless mineral containing aluminum, oxygen, potassium, and silicon.

megaslump
A very large (geological) slump.
A particularly significant (long, severe, etc) slump (period of poor performance).

megaslumps
plural of megaslump

meixnerite
A trigonal-hexagonal scalenohedral colorless mineral containing aluminum, hydrogen, magnesium, and oxygen.

melaconite
tenorite.

melanite
A black variety of andradite.

melanites
plural of melanite

melanochroite
Synonym of phoenicochroite.

melanochroites
plural of melanochroite

melanophlogite
A tetragonal-ditetragonal dipyramidal mineral containing carbon, hydrogen, oxygen, silicon, and sulfur.

melanophlogites
plural of melanophlogite

melanostibite
A trigonal-rhombohedral mineral containing antimony, iron, manganese, and oxygen.

melanotekite
An orthorhombic-disphenoidal mineral containing iron, lead, oxygen, and silicon.

melanothallite
An orthorhombic-dipyramidal mineral containing chlorine, copper, and oxygen.

melanovanadite
A triclinic-pinacoidal black mineral containing calcium, hydrogen, oxygen, and vanadium.

melaphyre
Various dark-coloured volcanic igneous rocks rich in augite, similar to and in some definitions including basalt, principally of Paleozoic age

melaphyres
plural of melaphyre

melatope
An eye shape of concentric coloured optical fringes seen on a conoscopic interference pattern surrounding an optical axis. For biaxial minerals there are a pair of circles, like eyes.

melatopes
plural of melatope

melatroctolite
A melanocratic troctolite.

melatroctolites
plural of melatroctolite.

melenite
Alternative spelling of melinite (“explosive”).

melilite
any mineral consisting of a solid solution of gehlenite (Ca₂Al₂SiO₇) and akermanite (Ca₂MgSi₂O₇)

melilites
plural of melilite