Redirecting select() output generates error

This is puzzling and I've no idea what to do to fix it.

   The table looks like this:

# select * from concentrations limit 2;
  site_nbr |  sampdate  | medium  | form  |   param   | quant | unit | cen | floor | ceiling 
----------+------------+---------+-------+-----------+-------+------+-----+-------+---------
  10332    | 1979-11-06 | surface | total | inorganic |   0.5 | ug/L |   1 |     0 |     0.5
  10332    | 1980-02-07 | surface | total | inorganic | 0.001 | ug/L |   1 |     0 |   0.001

Running this statement within psql works just fine (it's entered as a single
line but wrapped by alpine to fit the line limit):

select param, site_nbr, sampdate, min(quant), max(quant), unit from
concentrations group by param, site_nbr, sampdate, unit order by param,
site_nbr, sampdate, unit;

the output ends this way:

  organic   | 34198    | 2010-10-21 |   0.02 |  0.025 | ng/L
  organic   | 34198    | 2011-01-14 |   0.02 |  0.046 | ng/L
(585 rows)

   But, when I try to redirect output to a disk file like this,
\o data-summary-by-form.txt
the result is an error:

# select param, site_nbr, sampdate, min(quant), max(quant), unit from concentrations group by param, site_nbr,
sampdate,unit order by param, site_nbr, sampdate, unit;
 
ERROR:  syntax error at or near "|"
LINE 1: | 1980-05-08 |    0.5 |    0.5 | ug/L

   That line is not number 1 and I don't understand this behavior. Could it
be related to using hyphens in the filename rather than underscores?

Rich