  Chondritic meteorites contain unique spherical materials named chondrules:
sub-mm sized silicate grains once melted in a high temperature condition in the
solar nebula. We numerically explore one of chondrule forming processes,
planetesimal collisions. Previous studies found that impact jetting via
protoplanet-planetesimal collisions make chondrules with an amount of 1 % of
impactors' mass, when impact velocity exceeds 2.5 km s$^{-1}$. Based on the
mineralogical data of chondrules, undifferentiated planetesimals would be more
suitable for chondrule-forming collisions than potentially differentiated
protoplanets. We examine planetesimal-planetesimal collisions using a shock
physics code and find two things: one is that planetesimal-planetesimal
collisions produce the nearly same amount of chondrules as
protoplanet-planetesimal collisions ($\sim$ 1 %). The other is that the amount
of produced chondrules becomes larger as the impact velocity increases when two
planetesimals collide with each other. We also find that progenitors of
chondrules can be ejected from deeper regions of large targets (planetesimals
or protoplanets) than small impactors (planetesimals). The composition of
targets is therefore important to fully account for the mineralogical data of
currently sampled chondrules.
