Lithiophylite is a resinous reddish to yellowish brown mineral crystallizing in the orthorhombic system often as slender prisms. It is usually associated with lepidolite, beryl, quartz, albite, amblygonite, and spodumene of pegmatitic origin. It rather readily weathers to a variety of secondary manganese phosphates and oxides. It is a late-stage mineral in some complex granite pegmatites. Members of the triphylite-lithiophilite series readily alter to secondary minerals.
The type locality is the Branchville Quarry, Branchville, Fairfield County, Connecticut where it was first reported in 1878. The largest documented single crystal of lithiophilite was found in New Hampshire, US, measured 2.44×1.83×1.22 m3 and weighed ~20 tonnes.