Psilocybin is the major psychoactive agent in psilocybian mushrooms. The main difference between psilocybin and psilocin is their relative stabilities...psilocin is much more easily oxidized, so deteriorates much more quickly than psilocybin. The following chart shows approximate oral dosages of psilocybin in mg.

Oral Psilocybin Dosages Threshold 2 - 4 mg Light 4 - 8 mg Common 6 - 20 mg Strong 20 - 40 mg Heavy 35 + mg

Onset : 15 - 20 minutes (when held in mouth) Duration : 2 - 6 hours Normal After Effects : up to 8 hours

Notes:

• In 2006, Griffiths et al published research in which subjects were administered .43mg/kg psilocybin (30mg per 70kilogram adult) and 61% of participants experienced a "complete" mystical experience. (Griffiths RR, Richards WA, McCann U, Jesse R. "Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance". Psychopharmacology. 2006)
• In the early 1960s, Sandoz Pharmaceutical sold psilocybin in pink 2mg pills. "The literature on mushroom research suggested using doses of 8 milligrams and each pill was 2 milligrams." (Leary T. High Priest 1995. pg 71.)
• Timothy Leary's first use of Sandoz psilocybin was 4mg, which he reported as a light but clearly above-threshold dose. His friends took 12mg and 14mg and had clear effects, including some visuals and altered/intoxicated behavior.
• Rick Strassman's research administering psilocybin to subjects involved both .45mg/kg and 0.9mg/kg oral psilocybin. At 0.45mg/kg the "subjects' experiences were strong, fully psychedelic. They could get out of bed but didn't want to." And at 0.9mg/kg "they were pretty immobilized, but in touch with [researchers] when [they] needed to make contact." (R. Strassman, personal communication). A .45mg/kg dose would be around 30mg for a 150 pound person.
• Fischer and Thatcher administered .16mg/kg to subjects and described it as "mildly hallucinogenic" and "a dose which in most cases induces mild hallucinations in only some subjects". This dose caused small changes in visual perception, handwriting, and ability/willingness to perform dull tests. (Fischer 1970)
• Leary et al. administered between 20 and 70mg of psilocybin in their "Prisoner Rehabilitation" program, but settled on "30 mg. as a standard, moderate dose". However, word choice could get in the way here: 'moderate' may mean many things. Leary, later in the same paper, says "Psilocybin produces temporary states of spiritual conversion, interpersonal closeness and psychological insight. Forty-five percent of the entire inmate group clearly underwent a mystical, transcendent, death-rebirth experience. This figure should be modified, however. The results for running sessions improved so that 100% of our recent groups were undergoing transcendent experiences." The term 'moderate' must be read in the context where 100% of those moderate doses precipitated "transcendent" experiences. (Leary 1969)