orthochlorite (or-tho-chlo'-rite). (a) A group name for distinctly crystalline forms of chlorite (such as clinochlore and penninite). (b) A group name for chlorites conforming to the general formula: (M²⁺,M³⁺)₆(OH)₈[(Si,Al)₄O₁₀]. (Hey, 1962, p.546). Cf: leptochlorite.